Distance measuring device

Abstract

To provide a distance measuring device capable of measuring a distance at high speed while suppressing measurement variability and easily distinguishing a signal component of a received light signal from a noise component.SOLUTION: The distance measuring device includes: a light projection element that projects pulsed light according to a light projection cycle; a light receiving element that receives light obtained by reflecting the pulsed light by an object to be detected and generates a received light signal; a binarization processing unit that binarizes the received light signal to generate a binary signal; a waveform data generation unit that generates binarized waveform data which is waveform data showing changes in the binary signal for a light receiving section which is a time of one cycle of a light receiving cycle corresponding to a time of one cycle of a light projection cycle; a correlation processing unit that derives correlation coefficient data showing a correlation between the binarized waveform data and reference waveform data; and a distance measurement unit that measures a distance to a target object based on a first peak time position where a correlation coefficient of the correlation coefficient data is a time position of a peak value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to distance measuring devices. [Background technology]

[0002] It has been known in the art to optically detect an object or measure the distance using a light-emitting element and a light-receiving element. For example, a method for measuring the distance to at least one target, which includes transmitting at least one optical pulse from a transmitter to the target, capturing the reflection of at least one pulse by a receiver, converting it into a received signal, and storing it, and then detecting the propagation time from the reception time of the input signal and calculating the distance therefrom, is known, in which, to detect at least one reception time point, the input signal is compared with a comparison function, which is an example of a previously detected and stored reference function shifted by various time intervals, and the reception time point is at least approximately detected from the time interval corresponding to the most similar comparison function (see Patent Document 1).

[0003] Also known is a photoelectric sensor that includes a light-emitting element that repeatedly generates detection light, a light-receiving element that receives reflected light of the detection light, a binarization processing unit that binarizes the received light signal, a waveform detection unit that detects waveform data that indicates the time change of the binarized received light signal, a waveform integration unit that synchronizes the light emission timing of the light-emitting element to integrate two or more waveform data and generate integrated waveform data, and a work discrimination unit that determines whether or not a work is present based on the integrated waveform data (see Patent Document 2).

[0004] Also known is a TOF (Time Of Flight) sensor that detects an object or measures the distance to the object using TOF, which indicates the time from the time a light pulse is emitted to the time a reflected pulse is received. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-304862 [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-075453 Summary of the Invention [Problem to be solved by the invention]

[0006] In a device implementing the method of Patent Document 1, if the signal strength of the received light signal based on the reflected light from an object is low, i.e., if the signal strength is low, it may be difficult to distinguish between the signal component of the received light signal and noise, which reduces the accuracy of distance measurement by this device.

[0007] The photoelectric sensor in Patent Document 2 digitizes an analog light-receiving signal, integrates the waveform multiple times (for example, 64 times), and calculates one distance value based on this integrated waveform. Therefore, this photoelectric sensor needs to integrate the waveform multiple times before calculating one distance value, which takes time.

[0008] The present disclosure has been made in consideration of the above circumstances, and provides a distance measurement device that can easily distinguish signal components of a received light signal from noise components, suppress measurement variations, and measure distances at high speed. [Means for solving the problem]

[0009] One aspect of the present disclosure is a distance measurement device comprising: a light-projecting element that projects pulsed light in accordance with a light-projection cycle; a light-receiving element that receives light reflected from an object to be detected and generates a light-receiving signal; a binary processing unit that binarizes the light-receiving signal to generate a binary signal; a waveform data generation unit that generates binary waveform data that is waveform data that shows changes in the binary signal for a light-receiving interval that is one cycle of a light-receiving cycle corresponding to one cycle of the light-projection cycle; a correlation processing unit that derives correlation coefficient data that shows the correlation between the binary waveform data and reference waveform data; and a distance measurement unit that measures the distance to the object based on a first peak time position, which is the time position at which the correlation coefficient of the correlation coefficient data reaches its peak value. [Effects of the Invention]

[0010] According to the present disclosure, the signal component of the received light signal can be easily distinguished from the noise component, and the measurement variation can be suppressed to measure the distance at high speed. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram illustrating an example of the configuration of a distance measurement device according to an embodiment of the present disclosure. [Figure 2] FIG. 10 is a diagram showing an example of a received light signal. [Figure 3] FIG. 1 is a diagram showing an example of a binary signal. [Figure 4] A diagram showing an example of correlation coefficient data [Figure 5] FIG. 10 is a diagram showing an example of reference waveform data. [Figure 6] FIG. 10 is a diagram showing an example of correlation coefficient data in which a peak time position has a peak time width. [Figure 7] FIG. 10 shows a first example of derivation of peak time positions for distance measurement using a histogram. [Figure 8] FIG. 10 shows a second example of derivation of peak time positions for distance measurement using a histogram. [Figure 9] FIG. 10 shows a third example of derivation of peak time positions for distance measurement using a histogram. [Figure 10] Flowchart showing an example of the operation of a distance measuring device [Figure 11] FIG. 1 is a diagram showing an example of a signal or data obtained by a distance measuring device in time series. [Figure 12] FIG. 10 is a diagram showing an example of a simulation result of the range of variation in distance values, measurement variation, and response time. [Figure 13] A diagram showing an example of the relationship between the PD current and the range of variation in distance values. [Figure 14] A diagram showing an example of the relationship between the PD current and the peak value of the correlation coefficient. [Figure 15] An example of the relationship between PD current and peak time width [Figure 16] 10 is a diagram showing an example of the relationship between the PD current and the width of the variation in the distance value for each of the present embodiment, Comparative Example 1, and Comparative Example 2. [Figure 17] FIG. 10 is a diagram showing an example of the relationship between the response speed and the range of variation in distance values ​​when a signal is of high strength, for each of the present embodiment, Comparative Example 1, and Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters or descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0013] Furthermore, the term "unit" or "device" in the embodiments is not limited to a physical configuration mechanically realized by hardware, but also includes a configuration whose functions are realized by software such as a program. Furthermore, the functions of one configuration may be realized by two or more physical configurations, or the functions of two or more configurations may be realized by one physical configuration.

[0014] <Configuration of distance measuring device> FIG. 1 is a block diagram showing an example configuration of a distance measurement device 100 according to an embodiment of the present disclosure. The distance measurement device 100 derives (e.g., calculates) the time of flight of light according to a TOF (Time Of Flight) method and measures (e.g., calculates) a distance based on the time of flight. The time of flight is the difference between the projection timing (light projection time) of a predetermined projected light and the reception timing (light reception time) of the received light that is the projected light reflected by a detected object. Furthermore, the distance measurement device 100 detects the presence or absence of a detection target object (detected object) and detects (measures) the distance between the distance measurement device 100 and the detected object based on the time of flight of light according to, for example, the TOF method.

[0015] The distance measurement device 100 is a TOF sensor, a distance measurement sensor, an object detection sensor, etc., and is, for example, a one-dimensional distance measurement device (1D-TOF). In a 1D-TOF, the light intensity of the projected light and the received light tends to be small, and the signal level (signal intensity) of the received light signal tends to be small.

[0016] The distance measurement device 100 includes a light emitting element 110, a light receiving element 120, a processor 130, a memory 130M, and an output device 140.

[0017] The light-projecting element 110 includes a light-emitting element such as a laser diode, and projects a predetermined light. The light-projecting element 110 projects, for example, invisible light (e.g., infrared light), and may also project visible light. The light projected by the light-projecting element 110 (also referred to as projected light) may be reflected, for example, by the detection object 50. The detection object 50 is an object to be detected. The light-projecting element 110 projects light in accordance with light-projection conditions (e.g., light-projection timing, light-projection cycle, and number of light projections) determined by the control unit 131. The projected light EL is, for example, pulsed light.

[0018] The light receiving element 120 includes a light receiving element such as a photodiode (PD) and receives predetermined light. The light receiving element 120 receives, for example, invisible light (e.g., infrared light) and may also receive visible light. The light received by the light receiving element 120 (also referred to as received light) may include detection light that is generated when the projected light EL projected by the light projecting element 110 is reflected by the detection body 50. The light receiving element 120 generates a light reception signal from the received light RL. Furthermore, the light receiving element 120 receives the received light RL at a light reception timing corresponding to the light projection timing.

[0019] Fig. 2 is a diagram showing an example of a received light signal RS, in which the horizontal axis represents time and the vertical axis represents the amplitude (signal level) of the received light signal (signal before binarization).

[0020] The binarization processing unit 125 receives the light-receiving signal from the light-receiving element 120. The binarization processing unit 125 binarizes the light-receiving signal according to its signal level to generate a binary signal. The binary signal is at a predetermined High level while the level of the light-receiving signal is equal to or greater than a predetermined threshold th1, and is at a predetermined GND level while the level of the light-receiving signal is less than the threshold th1. The High level is higher than the GND level. The binarization processing unit 125 is configured, for example, by a comparator circuit.

[0021] Fig. 3 is a diagram showing an example of the binary signal NS, in which the horizontal axis represents the time direction and the vertical axis represents the amplitude (signal level) of the binary signal.

[0022] The processor 130 may be configured to include an MPU (Micro Processing Unit), a CPU (Central Processing Unit), a DSP (Digital Signal Processor), etc. The processor 130 may be configured with various integrated circuits (e.g., LSI (Large Scale Integration), FPGA (Field Programmable Gate Array)).

[0023] The processor 130 realizes various functions by executing programs stored in the memory 130M. The processor 130 includes, as various functional units, a control unit 131, a signal processing unit 132, and a distance measurement unit 135. The signal processing unit 132 includes a waveform data generation unit 133 and a correlation processing unit 134. Note that, although the configuration has been shown in which data and information are stored in memory 130M that is external to the processor 130, this is not limitative. Data and information may also be stored in memory within the processor 130 (i.e., the memory 130M is built into the processor).

[0024] The control unit 131 generates (determines) the light projection timing at which the light projecting element 110 projects the projected light EL, and controls the light projection timing. The light projection timing may be determined by the light projection conditions. The light projection conditions may include a light projection period tp, a number of light projections tn, various characteristics of the projected light EL (for example, the amount of light (power), amplitude, pulse width, or frequency) of the projected light EL, etc. The light projection conditions may be stored in the memory 130M.

[0025] In this case, the waveform data generation unit 133 samples the binary signal at a predetermined sampling rate (e.g., 0.5 ns or less) using, for example, a TDL (Tapped Delay Line) and memory 130M to obtain binary waveform data ND as a digital signal. Specifically, the waveform data generation unit 133 divides the binary signal into periods (light-reception intervals) corresponding to one light-reception period of the light-projection period tp, in accordance with the light-reception timing based on the light-projection timing determined by the control unit 131. The light-projection period tp and the light-reception period are the same. The waveform data generation unit 133 then generates waveform data (binarized waveform data) indicating changes in the binary signal over time relative to the light-reception intervals. At this time, the waveform data generation unit 133 controls (e.g., delays) the timing so that the binary signal is at least temporarily stored in the memory 130M as binary waveform data ND indicating changes over time. The waveform data generating section 133 may generate binary waveform data ND for a plurality of different light receiving intervals in time series from the binary signal.

[0026] The correlation processing unit 134 derives (e.g., calculates) correlation coefficient data CD indicating the correlation between the binarized waveform data and the reference waveform data. The correlation coefficient data CD is data indicating changes in the correlation coefficient over time. The correlation coefficient is an index indicating the strength of the relationship (correlation) between two types of data. The correlation coefficient y(t) is expressed, for example, by the following (Equation 1):

[0027]

number

[0028] In Equation 1, x(τ) represents the binarized waveform data ND, and g(t-τ) represents the reference waveform data SD. That is, the correlation processing unit 134 calculates the correlation coefficient y(t) of the correlation coefficient data CD based on the binarized waveform data ND and the reference waveform data SD. The reference waveform data SD is stored in, for example, memory 130M.

[0029] 4 is a diagram showing an example of correlation coefficient data CD. The horizontal axis of FIG. 4 represents time, and the vertical axis represents the coefficient value of the correlation coefficient. Furthermore, the correlation processing unit 134 may calculate the correlation coefficient data CD based on the binarized waveform data ND and the reference waveform data SD for each of a plurality of different light-receiving intervals in a time series.

[0030] 5 is a diagram showing an example of the reference waveform data SD. The reference waveform data SD may be waveform data for a half wavelength of a sine wave. The distance measuring device 100 can obtain a correlation coefficient assuming an ideal case using this reference waveform data SD.

[0031] The reference waveform data may also be waveform data based on a received light waveform when projected light EL (e.g., pulsed light) projected from the light projecting element 110 is reflected by a predetermined reference detection object and received. Using this reference waveform data, the distance measurement device 100 can acquire a realistic correlation coefficient that assumes the case in which the distance measurement device 100 is used.

[0032] The distance measurement unit 135 measures (e.g., calculates) the distance from the distance measurement device 100 to the detection object 50 based on the correlation coefficient data CD derived by the correlation processing unit 134. In this case, the distance measurement unit 135 may derive (e.g., calculate) a peak time position PT (PT1), which is the time position at which the correlation coefficient of the correlation coefficient data CD reaches its peak value. The distance measurement unit 135 may measure the distance based on the peak time position PT1. The distance measurement unit 135 converts the peak time position calculated by the distance measurement unit 135 into a distance based on, for example, the speed of light. A method for deriving the peak time position PT1 will be described in detail later. The peak time position PT1 corresponds to the time position of the timing at which light is received by the light receiving element 120, and therefore the time of flight of light is derived by deriving the peak time position PT1.

[0033] The output device 140 outputs various types of information. The output device 140 may output data imperceptibly to the user of the distance measurement device 100 (for example, by outputting data to an output line or storing data in the memory 130M). The output device 140 may also include a presentation unit such as an indicator light (for example, an LED), a display, or a speaker, and output data perceptibly to the user (that is, by presenting the data to the user by display or sound output). The output device 140 may output information such as the amount of light received by the light receiving element 120 (signal level of the received light signal), the measured distance, the peak time position corresponding to the distance (that is, the time based on the time of flight of light), the presence or absence of the detected object 50, etc.

[0034] <Example of deriving peak time position> Next, an example of how to derive the peak time position PT1 will be described.

[0035] When correlation coefficient data CD is derived for multiple light-receiving intervals that differ in time series, multiple pieces of information on the time change of the correlation coefficient may be obtained, for example, as shown in FIG. 4. In this case, the peak value PV of the correlation coefficient differs for each light-receiving interval (correlation coefficient data CD), and the position of the peak time position PT (PT2) corresponding to the peak value PV also differs. The distance measurement unit 135 derives (e.g., calculates) the peak time position PT2 for each light-receiving interval. The distance measurement unit 135 calculates the peak time position PT1 for distance measurement based on the peak time position PT2 for each light-receiving interval.

[0036] For example, the distance measurement unit 135 may calculate the distance based on an average time position that is an average of the peak time positions PT2 for each light-receiving interval.

[0037] Furthermore, in the correlation coefficient data CD, the peak time position PT2 may have a predetermined time width (peak time width w) and form a peak time range PA. For example, if the signal level of the received light signal is a high-intensity signal equal to or higher than a predetermined level, the binary signal or binary waveform data may remain at a high level for a long period of time, resulting in a long period of time during which the correlation coefficient remains at its peak value. Figure 6 shows an example of correlation coefficient data CD in which the peak time position PT2 has a peak time width w.

[0038] For example, the distance measurement unit 135 may calculate a peak time position PT1 for distance measurement based on a center time position PTC (see FIG. 6) that is the center of the peak time range PA for each light receiving interval. Alternatively, the distance measurement unit 135 may calculate a peak time position PT1 for distance measurement based on a centroid time position that is the centroid of the peak time range PA. The centroid of the peak time range PA is a time position derived by (time of each point (each time position) × sum of correlation coefficients) ÷ (sum of correlation coefficients of each point) within a predetermined time period that includes the peak time range PA and the time around the peak time range PA. Note that the peak time position PT2 does not necessarily have to be a waveform having a peak time width w, and the centroid time position as the centroid may be calculated in the same manner as above for a predetermined time period that includes the peak time position PT2.

[0039] Furthermore, when the distance measurement unit 135 acquires correlation coefficient data CD for multiple light-receiving intervals that differ in time series, the distance measurement unit 135 may calculate a center time position PTC or a center-of-gravity time position of the peak time range PA for each light-receiving interval (each correlation coefficient data CD).The distance measurement unit 135 may then calculate a peak time position PT1 for distance measurement based on the multiple calculated center time positions PTC and center-of-gravity time positions.For example, the distance measurement unit 135 may calculate the peak time position PT1 for distance measurement based on a center average time position that is the average of the multiple center time positions PTC, or a center-of-gravity average time position that is the average of the multiple center time positions.

[0040] The distance measurement unit 135 may calculate a distance value for each light-receiving interval based on the peak time position PT2 for each light-receiving interval. The distance measurement unit 135 may calculate a final distance value by calculating a statistical value (for example, an average value) of the distance values ​​for each light-receiving interval based on the distance values ​​for each light-receiving interval.

[0041] <Example of deriving peak time position using time frequency information> When the distance measurement unit 135 acquires correlation coefficient data for multiple different light-receiving intervals in time series, the distance measurement unit 135 may generate time frequency information indicating the frequency of each peak time position PT2 based on the peak time position PT2 derived for each of the multiple light-receiving intervals. The time frequency information is expressed, for example, by a histogram (see FIG. 7, etc.). The distance measurement unit 135 may calculate a peak time position PT1 for distance measurement based on the time frequency information.

[0042] FIG. 7 is a diagram showing a first example of derivation of a peak time position PT1 for distance measurement using a histogram.

[0043] For example, the distance measurement unit 135 may map the peak time positions PT2 of each of the multiple correlation coefficient data CD to generate a histogram HT showing the frequency of each peak time position PT2. In the histogram HT, the peak time position PT1 for distance measurement may be calculated based on the peak time position PTH1 with the highest frequency (i.e., the highest frequency). For example, the distance measurement unit 135 may exclude peak time positions PT2 that are separated by a predetermined time t1 or more from the peak time position PTH1 with the highest frequency from the peak time positions PT2 for deriving the peak time position PT1 for distance measurement. In this case, the distance measurement unit 135 may calculate the peak time position PT1 for distance measurement based on each peak time position PT2 within the predetermined time t1 from the peak time position PTH1 with the highest frequency, for example, based on the average of these peak time positions PT2.

[0044] 7, the predetermined time t1 from the peak time position PTH1 includes both the time period before the peak time position PTH1 and the time period after the peak time position PTH1, but is not limited to this. The predetermined time t1 may be at least one of the time period before the peak time position PTH1 and the time period after the peak time position PTH1.

[0045] FIG. 8 is a diagram showing a second example of deriving the peak time position PT1 for distance measurement using a histogram.

[0046] For example, the distance measurement unit 135 may exclude peak time positions PT2 whose frequency is less than a threshold th2 in the histogram HT from the peak time positions PT2 used to derive the peak time positions PT1 for distance measurement. In this case, the distance measurement unit 135 may calculate the peak time positions PT1 for distance measurement based on the peak time positions PT2 whose frequency is equal to or greater than the threshold th2, for example, based on the average of these peak time positions PT2.

[0047] FIG. 9 is a diagram showing a third example of deriving the peak time position PT1 for distance measurement using a histogram.

[0048] For example, the distance measurement unit 135 derives (e.g., extracts) the minimum (lowest) or minimal frequency from the frequencies of the peak time positions PT2 in the histogram HT. In the histogram, a minimal frequency peak time position PT2 is a time position where the frequencies of the peak time positions adjacent to the peak time position PT2 are all greater than the frequency of the peak time position PT2. The distance measurement unit 135 may calculate a peak time position PT1 for distance measurement based on each peak time position PT2 included between the peak time position PTH1 with the maximum frequency and a peak time position PTH3 adjacent to the peak time position PTH1 on the peak time position PTH1 side with respect to the peak time position PTH2 with the minimum or minimal frequency, for example, based on the average of these peak time positions PT2. In other words, the distance measurement unit 135 may exclude peak time positions PT2 outside the peak time position PT2 with the minimum or minimal frequency in the histogram HT from the peak time positions PT2 used to derive the peak time position PT1 for distance measurement.

[0049] Ideally, the peak time positions PT2 derived in different light-receiving intervals in a time series are the same time positions, but in reality they may vary. Even in this case, the distance measurement device 100 can quickly and reliably derive the peak time position PT1 for distance measurement by excluding data of the peak time positions PT2 with low reliability.

[0050] <Operation of distance measuring device> Next, the operation of the distance measurement device 100 will be described. Fig. 10 is a flowchart showing an example of the operation of the distance measurement device 100. Fig. 11 is a diagram showing an example of signals or data obtained by the distance measurement device 100 in time series.

[0051] First, the light projecting element 110 projects the projecting light EL (S11). The light receiving element 120 receives the received light RL, which is, for example, the projecting light EL reflected by the detection body 50 (S12). The light receiving element 120 acquires the received light signal RS as an analog signal based on the received light RL (S13). The binarization processing unit 125 generates a binarized signal NS based on the received light signal RS (S14). The waveform data generation unit 133 samples the binarized signal NS using, for example, a TDL, and generates binarized waveform data ND for the light receiving section (S15). The correlation processing unit 134 derives (e.g., calculates) correlation coefficient data CD based on the binarized waveform data ND and the reference waveform data SD (S16).

[0052] The distance measurement unit 135 calculates the peak time position PT2 in the light-receiving interval based on the correlation coefficient data CD (S17). The distance measurement unit 135 calculates the distance (distance value) to the detected object 50 based on the calculated peak time position PT2 (S18). The processor 130 determines whether a predetermined time (e.g., response time tr) has elapsed from the start of FIG. 10 using a timer (not shown) (S19). Note that the response time tr is mainly exemplified as the predetermined time here, but a time other than the response time tr may also be used. If the response time tr has not elapsed (No in step S19), the distance measurement device 100 proceeds to step S11 and repeats the processes of steps S11 to S19. That is, the distance measurement device 100 calculates the light-receiving signal RS, the binarized signal NS, the binarized waveform data ND, the correlation coefficient data CD, the peak time position PT2, and the distance value for the light-receiving interval subsequent to the above-mentioned light-receiving interval.

[0053] If the response time tr has elapsed (Yes in step S19), the distance measurement unit 135 calculates the peak time position PT1 for the final distance measurement based on the peak time position PT2 of each correlation coefficient data CD obtained for each light-receiving interval. The distance measurement unit 135 calculates the final distance (distance value) within the response time tr (S20).

[0054] Although the distance measurement unit 135 calculates the distance based on the peak time position PT2 for each light-receiving interval, this is not limiting. The distance measurement unit 135 may calculate one peak time position PT1 and calculate the distance based on the peak time position PT1, rather than calculating each distance based on the peak time position PT2 for each light-receiving interval. Alternatively, the distance measurement unit 135 may calculate the distance based on the peak time position PT2 for each light-receiving interval, and calculate the final distance within the response time tr based on the distance for each light-receiving interval.

[0055] <Considerations on distance measurement performance> Next, the measurement performance of the distance measurement by the distance measurement device 100 will be considered.

[0056] The correlation coefficient data CD obtained in multiple consecutive light-receiving intervals in time series may have different peak values ​​PV and peak time positions PT of the correlation coefficient, even when the same detected object 50 is detected and distances are measured. In other words, measurement variability σ occurs in distance measurements by the distance measurement device 100. The distance measurement unit 135 can estimate the width p of the variation in distance values ​​within a predetermined period (e.g., within a response time tr) (i.e., the distance measurement performance of the distance measurement device 100) using the measurement variability σ. The width p of the variation in distance values ​​is caused by the variation in peak time positions PT2 in each correlation coefficient data CD, and therefore also by the variation in distance values ​​derived based on each peak time position PT2. The variation in peak time positions PT2 or the variation in distance values ​​corresponds to the measurement variability σ. The distance measurement unit 135 may calculate the width p of the variation in distance values, for example, according to (Equation 2).

[0057]

number

[0058] Here, k is a coefficient, for example, 6, and p is the range of variation of the distance value. response (also simply written as tr) is the response time. period(also simply referred to as tp) is the light projection period. The response time tr is calculated by multiplying the light projection period tp by the number of light projections. For example, if the light projection period tp is 5 μs and the number of light projections is 100, the response time tr is 0.5 ms.

[0059] The distance measurement unit 135 can derive the response time tr according to the required range p of variation in distance values, for example, according to (Equation 2). Conversely, the distance measurement unit 135 can derive the range p of variation in distance values ​​according to the required response time tr, for example, according to (Equation 2).

[0060] FIG. 12 is a diagram showing an example of a simulation result of the width p of the variation in distance values, the measurement variation σ, and the response time tr.

[0061] For example, when a rough (rough) variation width p of the distance value is sufficient, the distance measurement device 100 can shorten the response time tr, that is, can measure the distance at high speed. For example, when a precise variation width p of the distance value is required, the distance measurement device 100 can measure the distance based on the average of the peak time positions PT2 for each light-receiving interval by lengthening the response time tr, and can derive the precise variation width p of the distance value.

[0062] For example, the processor 130 of the distance measurement device 100 may input the response time tr and calculate the range p of variation in distance values ​​according to the response time tr. That is, for example, even if the processor 130 specifies the minimum required response time tr and operates a line in a factory, the distance measurement device 100 can obtain an output based on the distance measurement result with a rough range p of variation in distance values.

[0063] FIG. 13 is a diagram showing an example of the relationship between the current (PD current) flowing through the light receiving element 120 and the width p of the variation in the distance value.

[0064] In Fig. 13, the horizontal axis showing the PD current is expressed logarithmically. This is the same for other figures showing PD current. The PD current is proportional to the amount of light received by the light-receiving element 120. In other words, when the amount of received light is large (for example, equal to or greater than a predetermined amount), the signal level of the received light signal RS is large, i.e., a high-intensity signal. When the amount of received light is small (for example, less than a predetermined amount), the signal level of the received light signal RS is small, i.e., a low-intensity signal.

[0065] 13, the smaller the PD current, the larger the variation p of the distance value. That is, the range of possible peak time positions PT2 corresponding to the peak time positions PT2 derived by the distance measurement device 100 is large, and the deviation (variation) from the actual peak time positions PT2 is large. Therefore, the range of possible distances corresponding to the distances derived by the distance measurement device 100 based on the peak time positions PT2 is large, and the deviation (variation) from the actual distance is large.

[0066] On the other hand, the larger the PD current, the smaller the variation p of the distance value. In other words, the range of possible peak time positions PT2 corresponding to the peak time positions PT2 derived by the distance measurement device 100 is small, and the deviation (variation) from the actual peak time positions PT2 is small. Therefore, the range of possible distances corresponding to the distances derived by the distance measurement device 100 based on each peak time position PT2 is small, and the deviation (variation) from the actual distance is small. Therefore, high-intensity signals have better measurement performance than low-intensity signals.

[0067] <Specifying and deriving parameters related to distance measurement> Next, examples of specifying and deriving parameters related to the measurement performance of distance measurement will be described.

[0068] The above-mentioned (Equation 2) includes the parameters of the range of variation p of distance values, coefficient k, measurement variation σ, response time tr, and light projection period tp. These parameters are parameters related to measurement performance. Information on (Equation 2) and information on each parameter may be stored in memory 130M. If coefficient k is known, control unit 131 may derive (e.g., calculate) the remaining one parameter by making the three parameters known (e.g., specifying them).

[0069] For example, the control unit 131 may calculate the width p of the distance value variation by setting (e.g., specifying) the coefficient k, the measurement variation σ, the response time tr, and the light-projection cycle tp to known values. The control unit 131 may calculate the light-projection cycle tp by setting the coefficient k, the measurement variation σ, the width p of the distance value variation, and the response time tr to known values. The control unit 131 may calculate the measurement variation σ by setting the coefficient k, the response time tr, the light-projection cycle tp, and the width p of the distance value variation to known values. The control unit 131 may calculate the response time tr by setting the coefficient k, the light-projection cycle tp, the width p of the distance value variation, and the measurement variation σ to known values. Because the response time tr is based on the light-projection cycle tp and the number of light projections tn, the light-projection cycle tp and the number of light projections tn may be specified and derived instead of the response time tr.

[0070] For example, the control unit 131 may specify at least one of the number of light projections tn, the light projection period tp, the measurement variation σ, and the width p of the variation in the distance value, and derive (e.g., calculate) the response time tr, which is the time required to measure the distance, based on the specified at least one piece of information.

[0071] In specifying the parameters, for example, the control unit 131 may specify the parameters by accepting an operation to input the parameters from a user via an operation device included in the distance measurement device 100. For example, the control unit 131 may specify the parameters by inputting information about the parameters from an external device via an input device included in the distance measurement device 100. For example, the control unit 131 may specify the parameters by receiving information about the parameters from an external device via a communication device included in the distance measurement device 100.

[0072] In other words, the distance measuring device 100 can measure the distance to the detected object 50 while satisfying the parameter conditions that the user values, for example, by specifying the parameter values ​​(i.e., parameter conditions) that the user values, even if there are some system constraints.

[0073] Furthermore, when measuring distance by specifying parameters including the response time tr, the control unit 131 may measure (actually measure) the response time tr using a timer included in the processor 130. In this case, the control unit 131 may determine whether the actual measured value of the response time tr is equal to or less than a specified or derived value of the response time tr, i.e., whether the required response performance is satisfied. If the actual measured value of the response time tr is longer than the specified or derived value of the response time tr, i.e., if the required response performance is not satisfied, the control unit 131 may modify at least one of the parameters related to distance measurement. The parameters to be modified here include at least one of the coefficient k, the light-projection period tp, the number of light-projections tn, the range p of variation in distance values, and the measurement variation σ.

[0074] Furthermore, the control unit 131 may set the operation mode of the distance measurement device 100. The settable operation modes may include a performance-oriented mode and a responsiveness-oriented mode. The performance-oriented mode is an operation mode in which the parameters of (Equation 2) are automatically adjusted with emphasis on the width p of the variation in distance values. Emphasizing the width p of the variation in distance values ​​includes making the width p of the variation in distance values ​​as small as possible. The responsiveness-oriented mode is an operation mode in which the parameters of (Equation 2) are automatically adjusted with emphasis on responsiveness. Emphasizing responsiveness includes making the response time tr as short as possible, that is, making the number of light projections tn as small as possible and making the light projection period tp as short as possible.

[0075] The distance measuring device 100 allows the user to easily set the parameters that should be emphasized, even if the user does not understand how to adjust and set the parameters in (Equation 2), by allowing the user to set the operating mode to a performance-oriented mode or a responsiveness-oriented mode.

[0076] Furthermore, the control unit 131 may calculate the response time tr for each of the performance-oriented mode and the responsiveness-oriented mode, for example, according to (Equation 2), and output information regarding the response time tr via the output device 140. This allows the user to check whether the response time tr desired by the set operation mode, either the performance-oriented mode or the responsiveness-oriented mode, is met by checking the output (e.g., displayed) information. This allows the user to make a final decision on whether the set operation mode is acceptable.

[0077] <Example of low and high signal strength determination> Next, an example of determining whether a low-intensity signal or a high-intensity signal is present will be described.

[0078] FIG. 14 is a diagram illustrating an example of the relationship between the PD current and the peak value PV of the correlation coefficient.

[0079] The correlation coefficient data CD is based on the binarized waveform data ND and the reference waveform data SD. Therefore, the correlation coefficient data CD tends to have a larger peak value PV of the correlation coefficient as the amount of received light increases, and a smaller peak value PV of the correlation coefficient as the amount of received light decreases. Therefore, when the PD current is greater than threshold th3, the peak value PV is equal to or greater than threshold th4, which can be said to be a high-intensity signal. On the other hand, when the PD current is equal to or less than threshold th3, the peak value PV is less than threshold th4, which can be said to be a low-intensity signal.

[0080] Therefore, the control unit 131 may determine whether the light reception signal RS is a high-intensity signal or a low-intensity signal based on the peak value PV of the correlation coefficient of the correlation coefficient data CD for each light-receiving interval, for example, based on the average of the peak values ​​PV for each light-receiving interval. The control unit 131 may determine the light reception signal RS as a high-intensity signal when the peak value PV is equal to or greater than a threshold value th4, and may determine the light reception signal RS as a low-intensity signal when the peak value PV is less than the threshold value th4.

[0081] 14, the peak value PV is shown as an average of the peak values ​​PV of the correlation coefficients in 100 pieces of correlation coefficient data CD, but is not limited to this. For example, even if the peak value PV in one piece of correlation coefficient data CD is shown, the relationship between the PD current and the peak value PV may be close to the state shown in FIG.

[0082] FIG. 15 is a diagram illustrating an example of the relationship between the PD current and the peak duration w.

[0083] The correlation coefficient data CD is based on the binarized waveform data ND. The longer the period during which the amount of received light is high, the longer the duration of the binarized waveform data ND becomes at a high level, and the longer the peak duration w becomes. Therefore, when the PD current is greater than threshold th3, the peak duration w becomes longer than a predetermined threshold th5 (e.g., 2 ns), and it can be said to be a high-intensity signal. On the other hand, when the PD current is equal to or less than threshold th3, the peak duration w is equal to or less than threshold th5, and it can be said to be a low-intensity signal.

[0084] Therefore, the control unit 131 may determine whether the received light signal RS is a high-intensity signal or a low-intensity signal based on the peak time width w for each light-receiving interval, for example, based on the average of the peak time width w for each light-receiving interval.

[0085] 15, the peak time width w is shown as an average of the peak time widths w of 100 pieces of correlation coefficient data CD as an example, but is not limited to this. For example, even if the peak time width w of one piece of correlation coefficient data CD is shown, the relationship between the PD current and the peak time width w may be close to the state shown in FIG.

[0086] The control unit 131 may adjust (control, for example, change) the response time tr based on whether the received light signal RS is a low-intensity signal or a high-intensity signal. For example, the control unit 131 may adjust the response time tr so that it is longer when the received light signal RS is a low-intensity signal than when the received light signal RS is a high-intensity signal. This is because a low-intensity signal has a larger variation p in distance values ​​than a high-intensity signal, resulting in lower accuracy. By ensuring a longer response time tr, the distance measurement device 100 can reduce the variation p in distance values ​​and improve distance measurement accuracy.

[0087] In this way, the distance measurement device 100 can determine whether the received light signal RS is a low-intensity signal or a high-intensity signal, and can measure the distance under optimal conditions (for example, by changing the response time tr) depending on whether the received light signal RS based on reflection from the detection object 50 is a low-intensity signal or a high-intensity signal. This allows the user to automatically obtain an output based on the measured distance under optimal conditions without considering whether the received light signal RS based on reflection from the detection object 50 is a low-intensity signal or a high-intensity signal.

[0088] Furthermore, the control unit 131 may output information regarding whether the received light signal RS is a low-intensity signal or a high-intensity signal via the output device 140. This allows the user to manually adjust the response time tr, for example, via an operation device, by checking the output (e.g., displayed) information. In this case, the user may manually adjust the response time tr so that it is longer when the received light signal is a low-intensity signal than when the received light signal is a high-intensity signal.

[0089] <Comparison between this embodiment and comparative example> Next, this embodiment will be compared with comparative examples (Comparative Example 1 and Comparative Example 2). Comparative Example 1 is the result of measuring the distance using the method of Patent Document 1, and Comparative Example 2 is the result of measuring the distance using the device of Patent Document 1.

[0090] FIG. 16 is a diagram showing an example of the relationship between the PD current and the width p of the variation in the distance value for each of the present embodiment, the comparative example 1, and the comparative example 2. In FIG.

[0091] 16 shows the measurement results obtained by Comparative Example 1, Comparative Example 2, and this embodiment. As described above, the larger the PD current, the larger the signal level and the stronger the signal, and the smaller the PD current, the smaller the signal level and the weaker the signal.

[0092] 16, in Comparative Example 1, Comparative Example 2, and this embodiment, the larger the PD current, the smaller the width p of the variation in distance values. The difference between the width p of the variation in distance values ​​between Comparative Example 1, Comparative Example 2, and this embodiment is small. Meanwhile, in Comparative Example 1, Comparative Example 2, and this embodiment, the smaller the PD current, the larger the width p of the variation in distance values. In particular, in Comparative Example 1, the width p of the variation in distance values ​​is large, about twice that of this embodiment. In Comparative Example 2, the width p of the variation in distance values ​​is also larger than that of this embodiment.

[0093] FIG. 17 is a diagram showing an example of the relationship between the response speed and the width p of the variation in distance values ​​when a signal strength is high, for each of this embodiment, Comparative Example 1, and Comparative Example 2.

[0094] In FIG. 17, the slower the response speed, the smaller the variation width p of the distance values. This is because a longer time can be secured for measuring the distance. On the other hand, the faster the response speed, the larger the variation width p of the distance values. This is because a sufficient time cannot be secured for measuring the distance. In particular, the variation width p of the distance values ​​is larger in Comparative Example 2. Comparative Example 1 also has a larger variation width p of the distance values ​​than this embodiment. Furthermore, this embodiment can reduce the response time tr to about 1 / 10 in order to obtain a variation width p of the distance values ​​equivalent to that of Comparative Example 2 when a high-intensity signal is received. Therefore, this embodiment can improve responsiveness to 1 / 10 compared to Comparative Example 2.

[0095] In this way, the distance measurement device 100 of this embodiment derives the binarized waveform data showing the time change of the binarized signal for the light receiving section, the reference waveform data, and the correlation coefficient, and calculates the distance based on the peak value PV. Therefore, the distance measurement device 100 does not need to perform waveform integration, and can speed up processing. Furthermore, because the distance measurement device 100 calculates the distance based on relative change data using the correlation coefficient data CD, it can perform binarization according to the characteristics of the desired signal (a signal including light reflected by the detection object 50), improve the S / N ratio even at low signal levels, and calculate the distance with high accuracy.

[0096] Furthermore, the distance measurement device 100 can measure distances as quickly as possible while suppressing measurement variability σ (this σ corresponds to standard deviation) compared to conventional devices, regardless of whether the received light signal is a low-intensity signal or a high-intensity signal. For example, because the distance measurement device 100 can suppress measurement variability when the signal is low-intensity, it can suppress degradation of measurement performance even when determining the quantity of detected objects 50 (e.g., cardboard boxes or trays) of various colors (e.g., white, navy blue, or black) that tend to result in low-intensity signals using distance values. Furthermore, because the distance measurement device 100 can speed up distance measurement, it can improve the operating speed of a robot monitored by the distance measurement device 100 and measure the distance to a very small detected object 50 (e.g., a component) without slowing its movement speed as much as possible.

[0097] Furthermore, the distance measurement device 100 can increase the sampling rate by sampling the binary signal NS, and can retain the characteristics of the signal component of the detection light reflected from the detection object 50 even if the received light signal RS contains noise. Therefore, the distance measurement device 100 can increase the possibility of emphasizing the signal portion of this detection light using the correlation coefficient data CD, and can preferably detect this signal portion. Therefore, the distance measurement device 100 can reduce the measurement variation σ.

[0098] Furthermore, the distance measurement device 100 can obtain binary waveform data by high-speed sampling from the binary signal using, for example, a TDL. Furthermore, by using cross-correlation, the time required to derive the distance value can be shortened, as the binary waveform data does not need to be integrated, thereby speeding up distance measurement.

[0099] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0100] <Summary of Embodiments of the Present Disclosure> As described above, the embodiments of the present disclosure include at least the following: Note that, in parentheses, examples of components corresponding to the above-described embodiments are given, but the present disclosure is not limited to these.

[0101] (Item 1) a light-projecting element (light-projecting element 110) that projects pulsed light (light-projecting light EL) in accordance with a light-projection period (light-projection period tp); a light receiving element (light receiving element 120) that receives light (received light RL) that is the pulsed light reflected by an object to be detected (detection body 50) and generates a received light signal (received light signal RS); a binarization processing unit (binarization processing unit 125) that binarizes the received light signal to generate a binarized signal (binarized signal NS); a waveform data generating unit (waveform data generating unit 133) that generates binary waveform data (binarized waveform data ND) that is waveform data that indicates a change in the binary signal with respect to a light-receiving section that is a time period for one light-receiving period corresponding to a time period for one light-projecting period; a correlation processing unit (correlation processing unit 134) that derives correlation coefficient data (correlation coefficient data CD) that indicates the correlation between the binarized waveform data and reference waveform data (reference waveform data SD); a distance measurement unit (distance measurement unit 135) that measures the distance to the object based on a first peak time position (peak time position PT1) that is the time position of the peak value (PV) of the correlation coefficient of the correlation coefficient data; A distance measurement device (distance measurement device 100) comprising:

[0102] As a result, the distance measurement device 100 generates binary waveform data by sampling the binary signal obtained by binarizing the received light signal, and can therefore effectively distinguish between the signal component and the noise component of the received light signal even for low-intensity signals.In addition, the measurement device measures distance using correlation coefficient data without accumulating a large number of binary waveform data, thereby suppressing measurement variability and increasing measurement speed.

[0103] (Item 2) the waveform data generating unit generates the binarized waveform data for each of the light receiving sections into which the light receiving signal is divided in time; the correlation processing unit calculates the correlation coefficient data based on the binarized waveform data for each of the light receiving intervals; The distance measurement unit deriving a second peak time position (peak time position PT2) which is a time position at which the correlation coefficient of the correlation coefficient data has a peak value for each light-receiving interval; deriving the first peak time position based on the second peak time position for each of the light-receiving intervals; Item 1. A distance measuring device according to item 1.

[0104] As a result, the distance measurement device 100 derives the first peak time position based on the second peak time positions of multiple correlation coefficient data obtained for each light receiving interval, so that even if the accuracy of some of the second peak time positions is low, the accuracy of deriving the first peak time position can be prevented from decreasing.

[0105] (Item 3) the distance measurement unit derives the first peak time position based on an average of the second peak time positions for each of the light-receiving intervals. Item 2. A distance measuring device according to item 2.

[0106] This allows the distance measurement device 100 to derive, as the first peak time position, a representative time position of the second peak time positions of the plurality of correlation coefficient data obtained for each light-receiving interval. Therefore, the first peak time position can be derived with reduced variation in the second peak time position, thereby suppressing variation in distance measurements.

[0107] (Item 4) the second peak time position in the correlation coefficient data for each light-receiving interval forms a peak time range (peak time range PA) having a certain time width (peak time width w); The distance measurement unit calculating a central time position (central time position PTC) that is the center of the peak time range in the correlation coefficient data for each light-receiving section; deriving the first peak time position based on an average of the center time positions for each of the light-receiving intervals; Item 2. A distance measuring device according to item 2.

[0108] As a result, the distance measurement device often finds that the correlation coefficient data has symmetry along the time axis before and after the peak time position where the correlation coefficient peaks (for example, near or around the peak time position). In the case of a high-intensity signal, a peak time range is formed corresponding to the time when the binarized signal becomes a High level. Therefore, the distance measurement device can estimate that the center time position of the peak time range is the peak time position of the correlation coefficient data. Therefore, by calculating the average of these center time positions of each correlation coefficient data, the distance measurement device can reduce the variation in the center time position and derive the first peak time position, thereby reducing the variation in distance measurements.

[0109] (Item 5) the second peak time position in the correlation coefficient data for each light-receiving interval forms a peak time range having a certain time width; The distance measurement unit calculating a centroid time position, which is a centroid of a predetermined time including the peak time position in the correlation coefficient data, for each light-receiving interval; deriving the first peak time position based on an average of the center of gravity time positions for each of the light-receiving intervals; Item 2. A distance measuring device according to item 2.

[0110] As a result, the distance measurement device often finds that the time change in the correlation coefficient data is symmetric along the time axis before and after the peak time position where the correlation coefficient peaks (for example, near or around the peak time position). In the case of a high-intensity signal, a peak time range is formed corresponding to the time when the binarized signal becomes high level. Therefore, the distance measurement device can estimate that the centroid time position of the peak time range is the peak time position of the correlation coefficient data. Therefore, by calculating the average of these centroid time positions of each correlation coefficient data, the distance measurement device can reduce the variation in the centroid time position and derive the first peak time position, thereby reducing the variation in distance measurements.

[0111] (Item 6) The distance measurement unit deriving the frequency of each of the second peak time positions for each of the light receiving sections; deriving the first peak time locations based on the frequency of each of the second peak time locations; The distance measuring device according to any one of items 2 to 5.

[0112] This allows the distance measurement device to derive the first peak time position by taking into account the occurrence frequency of each second peak time position obtained for each light-receiving interval.

[0113] (Item 7) the distance measurement unit derives, as the first peak time position, an average of peak time positions within a predetermined time (predetermined time t1) from the second peak time position having the highest frequency; Item 6. A distance measuring device according to item 6.

[0114] This allows the distance measurement device to derive the first peak time position by excluding second peak time positions that are excessively far from the second peak time position with the highest frequency, thereby reducing the amount of calculation required to measure the distance.In addition, excluding second peak positions with large errors can improve the accuracy of distance measurement.

[0115] (Item 8) the distance measurement unit derives, as the first peak time position, an average of the second peak time positions whose frequency is equal to or greater than a predetermined frequency (threshold th2); Item 6. A distance measuring device according to item 6.

[0116] This allows the distance measurement device to derive the first peak time position while excluding the second peak time position, which occurs less frequently, thereby reducing the amount of calculation required to measure the distance.In addition, by excluding the second peak position, which has a large error, the distance measurement error can be reduced.

[0117] (Item 9) the distance measurement unit derives, as the first peak time position, an average of the second peak time positions between a third peak time position (peak time position PTH1) having the highest frequency and a fifth peak time position (peak time position PTH3) adjacent to the third peak time position with respect to a fourth peak time position (peak time position PTH2) having the lowest or minimum frequency, among the second peak time positions for each light receiving interval. Item 6. A distance measuring device according to item 6.

[0118] This allows the distance measurement device to derive the first peak time position by excluding second peak time positions outside the second peak time position of the minimum frequency or minimal frequency, thereby reducing the amount of calculation required to measure the distance.In addition, by excluding second peak positions with large errors, distance measurement errors can be reduced.

[0119] (Item 10) The reference waveform data is waveform data representing a waveform of a half wavelength of a sine wave. 10. The distance measuring device according to any one of items 1 to 9.

[0120] This allows the distance measurement device to obtain correlation coefficient data that takes into account ideal reflection conditions.

[0121] (Item 11) the reference waveform data is waveform data generated based on a light-receiving waveform obtained when the pulsed light projected from the light-projecting element is reflected by a reference detection object and received. 10. The distance measuring device according to any one of items 1 to 9.

[0122] This allows the distance measurement device to obtain correlation coefficient data that takes into account realistic reflection characteristics of the reference object. Also, the distance measurement device can minimize the influence of individual differences due to variations in parts, etc.

[0123] (Item 12) Further provided with a control unit (control unit 131), The control unit specifying at least one piece of information among the number of times light is projected by the light-projecting element (number of times light is projected tn), the light-projection cycle (light-projection cycle tp), the measurement variation of the distance (measurement variation σ), and the width of the measurement variation of the distance (width p of the variation of the distance value); Derive a response time (response time tr) that is a time required to measure the distance based on the at least one piece of specified information; outputting response time information relating to the response time; The distance measuring device according to any one of items 1 to 11.

[0124] This allows the distance measurement device to specify at least one piece of information (parameter) among the number of light projections, the light projection period, the measurement variability, and the width of the variability in distance measurement to a desired value, and the distance measurement device can provide the user with an output (for example, a display) of what response time the distance can be measured when the specified information is the desired value.

[0125] (Item 13) The control unit acquiring an actual measurement value of the response time; determining whether the actual value of the response time is less than or equal to the derived value of the response time; when it is determined that the actual measured value of the response time is longer than the derived value, correcting at least one piece of information among the number of light projections, the light projection period, the measurement variation, and the width of the variation in the distance measurement; Item 13. The distance measuring device according to item 12.

[0126] As a result, if the actual measured value of the response time is longer than the derived value (theoretical value taking each parameter into account), that is, if the actual measured value does not satisfy the responsiveness conditions, the distance measurement device can correct at least one of the above information that contributes to responsiveness so as to reduce the difference between the theoretical value and the actual measured value.

[0127] (Item 14) The control unit At least two operation modes of the distance measurement device can be selected: a performance-oriented mode that prioritizes the range of variation in the distance measurement, and a responsiveness-oriented mode that prioritizes the response time; deriving the response time for each of the performance-oriented mode and the responsiveness-oriented mode, and outputting the response time information; Item 13. The distance measuring device according to item 12.

[0128] This allows the distance measurement device to provide operation modes and information on the response time of each operation mode, so that the user can simply set the operation mode without having to understand each piece of information in detail and specify each value, and automatically adjust the values ​​of each parameter related to distance measurement in accordance with the operation mode of the distance measurement device that corresponds to the conditions desired by the user.

[0129] (Item 15) a control unit, the control unit determines whether the received light signal is a high-intensity signal or a low-intensity signal based on the peak value of the correlation coefficient of the correlation coefficient data for each of the light-receiving intervals. The distance measuring device according to any one of items 2 to 14.

[0130] The peak value of the correlation coefficient data corresponds to the amount of light received by the light receiving element, so the distance measurement device can easily determine whether the signal is high-intensity or low-intensity by recognizing the magnitude of the peak value of the correlation coefficient of this correlation coefficient data.

[0131] (Item 16) a control unit, the second peak time position in the correlation coefficient data for each light-receiving interval forms a peak time range having a certain time width; the control unit determines whether the received light signal is a high-intensity signal or a low-intensity signal based on an average of the time width for each of the light-receiving intervals. The distance measuring device according to any one of items 2 to 14.

[0132] The greater the amount of received light, the longer the period of high level in the binary signal and the longer the time width of the peak time range. Therefore, by recognizing the length of this time width, the distance measurement device can easily determine whether the signal is high intensity or low intensity.

[0133] (Item 17) a control unit, the control unit changes a response time, which is a time required to measure the distance, based on whether the received light signal is a high-intensity signal or a low-intensity signal. The distance measuring device according to any one of items 1 to 16.

[0134] This allows the distance measurement device to easily ensure a range of variation in distance measurements and measure distances quickly, even if the response time is shortened for high-intensity signals, for example.The distance measurement device can easily ensure a range of variation in distance values ​​even for low-intensity signals, for example, by lengthening the response time, and can improve distance measurement performance. [Industrial Applicability]

[0135] The present disclosure is useful for distance measuring devices and the like that can easily distinguish signal components of received light signals from noise components and can measure distances at high speed while suppressing measurement variations. [Explanation of symbols]

[0136] 50 Detected object 100 Distance measuring device 110 Light-emitting element 120 Photodetector 125 Binarization processing unit 130 processors 130M memory 131 Control Unit 132 Signal Processing Unit 133 Waveform data generation unit 134 Correlation processing unit 135 Distance measurement unit 140 output devices

Claims

1. a light-projecting element that projects pulsed light in accordance with a light-projection period; a light receiving element that receives the pulsed light reflected by an object to be detected and generates a light receiving signal; a binarization processing unit that binarizes the received light signal to generate a binary signal; a waveform data generating unit that generates binary waveform data that is waveform data that indicates a change in the binary signal with respect to a light-receiving section that is a time period corresponding to one cycle of the light-projecting cycle; and a correlation processing unit that derives correlation coefficient data that indicates the correlation between the binarized waveform data and reference waveform data; a distance measurement unit that measures a distance to the object based on a first peak time position that is a time position at which the correlation coefficient of the correlation coefficient data has a peak value; A distance measuring device comprising:

2. the waveform data generating unit generates the binarized waveform data for each of the light receiving sections into which the light receiving signal is divided in time; the correlation processing unit calculates the correlation coefficient data based on the binarized waveform data for each of the light receiving intervals; The distance measurement unit deriving a second peak time position, which is a time position at which the correlation coefficient of the correlation coefficient data has a peak value, for each of the light-receiving intervals; deriving the first peak time position based on the second peak time position for each of the light-receiving intervals; 2. A distance measuring device according to claim 1.

3. the distance measurement unit derives the first peak time position based on an average of the second peak time positions for each of the light-receiving intervals.

3. A distance measuring device according to claim 2.

4. the second peak time position in the correlation coefficient data for each light-receiving interval forms a peak time range having a certain time width; The distance measurement unit calculating a center time position that is the center of the peak time range in the correlation coefficient data for each light-receiving interval; deriving the first peak time position based on an average of the center time positions for each of the light-receiving intervals; 3. A distance measuring device according to claim 2.

5. the second peak time position in the correlation coefficient data for each light-receiving interval forms a peak time range having a certain time width; The distance measurement unit calculating a centroid time position, which is a centroid of a predetermined time including the peak time position in the correlation coefficient data, for each light-receiving interval; deriving the first peak time position based on an average of the center of gravity time positions for each of the light-receiving intervals; 3. A distance measuring device according to claim 2.

6. The distance measurement unit deriving the frequency of each of the second peak time positions for each of the light receiving sections; deriving the first peak time locations based on the frequency of each of the second peak time locations; 3. A distance measuring device according to claim 2.

7. the distance measurement unit derives, as the first peak time position, an average of peak time positions within a predetermined time from the second peak time position having the highest frequency; 7. A distance measuring device according to claim 6.

8. the distance measurement unit derives, as the first peak time position, an average of the second peak time positions whose frequency is equal to or greater than a predetermined frequency; 7. A distance measuring device according to claim 6.

9. the distance measurement unit derives, as the first peak time position, an average of the second peak time positions between a third peak time position having the highest frequency and a fifth peak time position adjacent to a fourth peak time position having the lowest or minimum frequency on the third peak time position side, among the second peak time positions for each light-receiving interval.

7. A distance measuring device according to claim 6.

10. The reference waveform data is waveform data representing a waveform of a half wavelength of a sine wave.

3. A distance measuring device according to claim 1 or 2.

11. the reference waveform data is waveform data generated based on a light-receiving waveform obtained when the pulsed light projected from the light-projecting element is reflected by a reference detection object and received.

3. A distance measuring device according to claim 1 or 2.

12. a control unit, The control unit specifying at least one of the number of times the light is projected by the light projecting element, the light projection period, the measurement variation of the distance, and the width of the measurement variation of the distance; deriving a response time, which is a time required to measure the distance, based on the at least one piece of specified information; outputting response time information relating to the response time; 3. A distance measuring device according to claim 1 or 2.

13. The control unit acquiring an actual measurement value of the response time; determining whether the actual value of the response time is less than or equal to the derived value of the response time; when it is determined that the actual measured value of the response time is longer than the derived value, correcting at least one piece of information among the number of light projections, the light projection period, the measurement variation, and the width of the variation in the distance measurement; 13. A distance measuring device according to claim 12.

14. The control unit At least two operation modes of the distance measurement device can be selected: a performance-oriented mode that prioritizes the range of variation in the distance measurement; and a responsiveness-oriented mode that prioritizes the response time; deriving the response time for each of the performance-oriented mode and the responsiveness-oriented mode, and outputting the response time information; 13. A distance measuring device according to claim 12.

15. a control unit, the control unit determines whether the received light signal is a high-intensity signal or a low-intensity signal based on the peak value of the correlation coefficient of the correlation coefficient data for each of the light-receiving intervals.

3. A distance measuring device according to claim 2.

16. a control unit, the second peak time position in the correlation coefficient data for each light-receiving interval forms a peak time range having a certain time width; the control unit determines whether the received light signal is a high-intensity signal or a low-intensity signal based on an average of the time width for each of the light-receiving intervals.

3. A distance measuring device according to claim 2.

17. a control unit, the control unit changes a response time, which is a time required to measure the distance, based on whether the received light signal is a high-intensity signal or a low-intensity signal.

3. A distance measuring device according to claim 1 or 2.

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