JP7383558B2 - Measuring device, measuring method, and program - Google Patents

Description

The present disclosure relates to a measuring device, a measuring method, and a program, and particularly relates to a measuring device, a measuring method, and a program that can measure distance with high precision in a shorter time.

Traditionally, TOF (Time of Flight), a technology that measures distance using the flight time of light, outputs a pulsed laser beam toward the object to be measured, and then the laser beam is directed toward the object to be measured. The time it takes for a pulse of reflected light to be received after being reflected off an object is measured. Then, the processing cycle of outputting pulsed laser light is repeated, a histogram of the measurement values measured in multiple processing cycles is generated, and the distance to the object to be measured is determined based on the measurement value that indicates the peak of the histogram. is calculated.

For example, Patent Document 1 discloses that by combining multiple light reception signals output from each of a plurality of light reception pixels, the detection performance of a measurement target located far away or a measurement target with low reflectance is improved. An optical ranging device is disclosed.

Japanese Patent Application Publication No. 2016-176750

By the way, in conventional TOF, for example, the laser beam is emitted at the same timing for each processing cycle (for example, at the same timing as the start of each processing cycle, or at the timing when the same fixed period of time has elapsed from the start of each processing cycle, etc.). When emitting pulses of

The present disclosure has been made in view of such circumstances, and is intended to enable distance measurement with high accuracy in a shorter time.

A measuring device according to an aspect of the present disclosure includes a firing timing signal generation unit that repeatedly generates a signal instructing a firing timing for emitting pulses of laser light at each predetermined processing cycle; a counter that continuously counts a count code indicating the timing of receiving a pulse in the reflected light reflected back at the switching of the processing cycle, and a time for delaying the emission timing from the start of the processing cycle. and a timing instruction section that instructs the emission timing signal generation section to set a different emission delay value for each processing cycle.

A measuring method or a program according to an aspect of the present disclosure includes the steps of: repeating every predetermined processing cycle to generate a signal instructing the firing timing to emit a pulse of laser light; and the laser light is reflected by an object to be measured. counting of a count code indicating the timing of receiving a pulse in the reflected light that has returned from the process is continued at the time of switching of the processing cycle; and firing indicating the time for delaying the firing timing from the start of the processing cycle. The method includes instructing a different delay value for each processing cycle.

In one aspect of the present disclosure, a signal instructing the firing timing for emitting pulses of laser light is generated repeatedly at each predetermined processing cycle, and reflected light that is reflected by the laser light from an object to be measured is returned. The count code that indicates the timing at which a pulse is received is continuously counted when the processing cycle changes, and the firing delay value that indicates the time to delay the firing timing from the start of the processing cycle is changed for each processing cycle. be instructed.

FIG. 1 is a block diagram showing a configuration example of an embodiment of a measuring device to which the present technology is applied. FIG. 2 is a diagram illustrating a processing cycle and pulse emission timing. It is a flowchart explaining the processing example of distance measurement processing. FIG. 6 is a diagram illustrating the effect of suppressing the occurrence of ghosts caused by pulses of reflected light detected outside the distance measurement range time. FIG. 6 is a diagram illustrating the effect of being able to perform distance measurement processing using a laser beam in which pulses are emitted two or more times within one processing cycle. FIG. 7 is a diagram illustrating the effect of canceling the influence of DNL on measurement accuracy. FIG. 3 is a diagram illustrating the effect of canceling the influence of DNL on measurement accuracy with a configuration in which upper bits and lower bits are separated. FIG. 3 is a diagram illustrating the influence of noise due to disturbance radio waves synchronized with a processing cycle. FIG. 6 is a diagram illustrating the effect of suppressing the influence of noise caused by disturbance radio waves synchronized with a processing cycle. FIG. 6 is a diagram illustrating a case where the pulse emission timing is not changed throughout the processing cycle. FIG. 6 is a diagram illustrating the effect of changing the maximum value of the count code. FIG. 6 is a diagram illustrating the effect of being able to shift the distance measurement range time. It is a figure which shows the modification of a ramp waveform. FIG. 7 is a diagram illustrating a processing example in which firing delay values are shifted at equal intervals in each processing cycle. FIG. 3 is a diagram illustrating a method of controlling laser irradiation timing and a method of processing TOF results. 12 is a flowchart illustrating a process in which a firing delay value is shifted in a predetermined pattern every processing cycle. FIG. 7 is a diagram illustrating the effect of canceling the influence of DNL on measurement accuracy when the firing delay value is shifted in a predetermined pattern for each processing cycle. FIG. 6 is a diagram showing a first example illustrating the shape of a ghost histogram due to the influence of out-of-range ToF. FIG. 7 is a diagram showing a second example illustrating the shape of a ghost histogram due to the influence of out-of-range ToF. 1 is a block diagram showing a configuration example of an embodiment of a computer to which the present technology is applied.

Hereinafter, specific embodiments to which the present technology is applied will be described in detail with reference to the drawings.

<Example of configuration of measuring device>
FIG. 1 is a block diagram showing a configuration example of an embodiment of a measuring device to which the present technology is applied.

The measuring device 11 shown in FIG. 1, for example, outputs a pulsed laser beam toward an object to be measured, and then receives a pulse of reflected light that is reflected back from the object to be measured. The distance to the target object is measured by measuring the time it takes to reach the distance. In Figure 1, even if a laser beam with four pulses is output to the object to be measured, if the object is far away, the three pulses indicated by the broken lines will not return. This means that only one pulse returns as reflected light.

As shown in FIG. 1, the measurement device 11 includes a firing timing signal generation section 12, a laser driver 13, a light receiving element 14, a TDC 15, a timing instruction section 16, a calculation section 17, a histogram generation section 18, and a distance calculation section 19. It consists of Further, the TDC 15 has a counter 21 and a latch 22. For example, in the measuring device 11, if each block is completely synchronized, each block can start a processing cycle in synchronization. Alternatively, in the measuring device 11, if the blocks are not completely synchronized, a signal notifying the start of the processing cycle is sent from the TDC 15 to the firing timing signal generation unit 12 and the timing instruction unit 16 as shown by the dashed arrow. Supplied.

The emission timing signal generation unit 12 generates a Tx pulse signal that instructs the emission timing for emitting pulses of laser light output from the measurement device 11 and supplies it to the laser driver 13 . At this time, the firing timing signal generation section 12 can delay the firing timing from the timing at which the processing cycle starts, according to the firing delay value supplied from the timing instruction section 16.

The laser driver 13 drives a laser light emitting element (not shown) according to the Tx pulse signal supplied from the emission timing signal generation section 12, and outputs pulsed laser light based on the emission timing.

The light-receiving element 14 is, for example, a SPAD (single photon avalanche diode), and receives the reflected light of the pulsed laser light reflected by the object to be measured, and generates an Rx pulse indicating the waveform of the reflected light. The signal is supplied to the latch 22 of the TDC 15.

A TDC (Time-to-Digital Conversion) 15 converts the time it takes for the laser beam output from the measurement device 11 to be reflected by an object to be measured and returned to a digital value. That is, the counter 21 starts counting up the count code at the start of the processing cycle, and the latch 22 takes in the count code from the counter 21 at the timing of the pulse indicated by the Rx pulse signal supplied from the light receiving element 14. Output.

The timing instruction unit 16 supplies a firing delay value indicating the time to delay the pulse firing timing from the start of the processing cycle to the firing timing signal generating unit 12 and the calculation unit 17, and determines the firing timing at which the pulse is fired from the measuring device 11. instruct. The timing instruction unit 16 can change the firing delay value for each processing cycle. As a result, in the measuring device 11, pulses are emitted at different emission timings from the start of the processing cycle for each processing cycle.

Hereinafter, in this embodiment, changing the firing timing at which pulses are fired every processing cycle according to the firing delay value instructed by the timing instruction unit 16 is referred to as pulse modulation.

The calculation unit 17 performs a calculation to subtract the firing delay value supplied from the timing instruction unit 16 from the count code supplied from the latch 22 of the TDC 15, and uses the value calculated by the calculation as a ToF value to the histogram generation unit 18. supply to. That is, the measuring device 11 outputs a pulsed laser beam so that the pulse is emitted at a firing timing delayed according to the firing delay value from the start of the processing cycle. Therefore, the calculation unit 17 subtracts the launch delay value from the count code indicating the timing at which the light receiving element 14 receives the pulse of reflected light, thereby corresponding to the flight time of the laser beam to and from the object to be measured. The ToF value can be found.

The histogram generation unit 18 generates a histogram of the ToF values calculated by the calculation unit 17. For example, in the measuring device 11, a plurality of processing cycles are repeatedly performed, and the histogram generation unit 18 generates a histogram using a plurality of ToF values corresponding to the repeated processing cycles. When a histogram is generated in which it is specified that a certain ToF value indicates a peak, the histogram generation unit 18 supplies the ToF value indicating the peak to the distance calculation unit 19.

The distance calculation unit 19 uses the ToF value supplied from the histogram generation unit 18 to calculate the distance to the object to be measured based on the speed of light.

Here, with reference to FIG. 2, the processing cycle in the measuring device 11 and the pulse emission timing will be explained.

TDC RAMP shown in FIG. 2 represents a ramp waveform that visualizes the count code counted by the counter 21 of the TDC 15, and the counter 21 repeatedly counts up from count code 0 in each processing cycle. Then, in the measuring device 11, the counter 21 starts counting up without delay (with 0 latency) from the timing at which the processing cycle starts, as indicated by TDC RAMP.

Therefore, in the measuring device 11, the TDC RAMP does not stop when the processing cycle changes, and the counter 21 continues counting, and although the count code is reset to 0, the counting does not stop. Thereby, in the measuring device 11, it becomes possible to overlap the ranging range time (ToF range) that starts at the timing when a pulse is output in a certain processing cycle in the next processing cycle. Note that the distance measurement range represents a certain range of distance that includes the distance between the distance measurement target and the distance measurement target, and the distance measurement range is a fixed distance range that includes the distance between the distance measurement target and the distance measurement target. The width of the flight time is hereinafter referred to as the distance measurement range time.

Furthermore, in the measuring device 11, the pulse is not emitted at the timing at which the processing cycle starts, but at a timing delayed from the start of the processing cycle according to the emission delay value DLY. Therefore, in the measuring device 11, the calculation unit 17 subtracts the launch delay value DLY from the count code at the timing when the pulse of the reflected light is detected, and calculates the time it takes for the light to travel back and forth between the distance and the object to be measured. The corresponding ToF value can be determined.

Further, in the measuring device 11, the timing instruction section 16 performs pulse modulation as described above to supply a different firing delay value DLY for each processing cycle to the firing timing signal generating section 12. That is, as shown in FIG. 2, the firing delay value DLY1 and the firing delay value DLY2 are different, and are adjusted for each processing cycle so that the interval from the start of the processing cycle until the pulse is emitted is not constant. .

In the measuring device 11 configured as described above, the counter 21 continues counting when the processing cycle changes, and the firing timing for emitting pulses can be made different for each processing cycle according to the firing delay value. . Thereby, the measuring device 11 can disperse the influence of ghosts (erroneous distance measurement) that occur when the distance measurement range times overlap, as will be described later. Therefore, the measuring device 11 can reach the object to be measured in a shorter time than a conventional configuration in which, for example, the distance measuring range time cannot be overlapped and an overhead time for pulse modulation is provided. Distance can be measured.

<Example of distance measurement processing>
The distance measurement process executed in the measuring device 11 will be described with reference to the flowchart shown in FIG.

For example, when control is performed to start distance measurement processing, the first processing cycle is started, and in step S11, the counter 21 starts counting up the count code.

In step S12, the timing instruction unit 16 supplies the firing timing signal generation unit 12 and the calculation unit 17 with a firing delay value indicating the time to delay the pulse firing timing from the start of the processing cycle.

In step S13, the firing timing signal generation unit 12 sends a Tx pulse signal to the laser driver 13 instructing the laser driver 13 to emit a pulse at a firing timing delayed from the start of the processing cycle according to the firing delay value supplied from the timing instruction unit 16 in step S12. supply Thereby, the laser driver 13 drives a laser light emitting element (not shown) to output pulsed laser light that emits pulses according to the emission timing indicated by the Tx pulse signal.

In step S14, the light receiving element 14 receives the reflected light of the pulsed laser light outputted in step S13, and supplies the latch 22 with an Rx pulse signal indicating the waveform of the reflected light. Thereby, the latch 22 takes in the count code from the counter 21 at the timing of the pulse indicated by the Rx pulse signal supplied from the light receiving element 14, and supplies it to the calculation section 17.

In step S15, the calculation unit 17 calculates the ToF value by subtracting the firing delay value supplied from the timing instruction unit 16 in step S12 from the count code supplied from the latch 22 in step S14, and calculates the ToF value. It is supplied to the generation unit 18.

In step S16, the histogram generation unit 18 generates a histogram using the plurality of ToF values supplied from the calculation unit 17 in step S15, which is performed repeatedly.

In step S17, the histogram generation unit 18 determines whether a peak of the ToF value has been identified in the histogram generated in the immediately preceding step S16, for example, whether a histogram showing a peak at a predetermined ToF value has been generated. judge.

In step S17, if the histogram generation unit 18 determines that the peak of the ToF value is not identified in the histogram generated in the immediately preceding step S16, the process returns to step S11. At this time, the counter 21 counts up to the maximum value of the count code, resets the count code to 0 at the next counting timing, and the second and subsequent processing cycles are repeated in the same manner.

On the other hand, if the histogram generation unit 18 determines in step S17 that the peak of the ToF value has been identified in the histogram generated in the immediately preceding step S16, the process proceeds to step S18. That is, the processing cycle is repeated until a histogram is generated that shows a peak at a predetermined ToF value.

In step S18, the histogram generation unit 18 supplies the ToF value identified as a peak in the histogram to the distance calculation unit 19. After the distance calculation unit 19 calculates the distance to the object to be measured using the ToF value, the process ends.

Through the measurement processing described above, the measuring device 11 can measure the distance to the object to be measured with high accuracy in a shorter time.

For example, by performing pulse modulation, the measurement device 11 generates a ToF value (hereinafter referred to as a ghost ToF value) that is different from the true ToF value according to the distance to the object to be measured, as described later with reference to FIG. It is possible to suppress the negative effects caused by the requirement of a value (referred to as a value). Thereby, the time required to measure the distance to the object to be measured can be shortened.

Furthermore, by continuously performing counting by the counter 21 at the time of switching the processing cycle, the measuring device 11 can set the ranging range time repeatedly, and as will be described later with reference to FIG. Distance measurement processing can be performed using a laser beam in which pulses are emitted two or more times within one processing cycle. As a result, more ToF values can be obtained in a short time, and peaks in the histogram can be identified more quickly.

In addition, by performing pulse modulation, the measuring device 11 cancels the influence of DNL on measurement accuracy, as will be described later with reference to FIGS. 6 and 7, and further improves measurement accuracy. be able to.

Furthermore, by performing pulse modulation, the measuring device 11 can suppress the influence of noise caused by disturbance radio waves synchronized with the processing cycle, as will be described later with reference to FIGS. 8 to 11, and can further improve measurement accuracy. You can improve your performance.

Furthermore, by continuously performing counting with the counter 21 when the processing cycle is switched, the measuring device 11 can set the ranging range time across the processing cycle, as will be described later with reference to FIG. 12. The distance measurement range time can be shifted accordingly.

<Effects of distance measurement processing>
With reference to FIGS. 4 to 12, the effects obtained by the distance measurement processing of the measuring device 11 as described above will be explained.

FIG. 4 is a diagram illustrating the effect of suppressing the occurrence of a ghost ToF value caused by a pulse of reflected light detected outside the distance measurement range time in the measuring device 11.

FIG. 4 shows processing cycles #1 to #3 that are repeated in a circular manner. Then, the counter 21 starts counting up from the timing when each processing cycle starts, and counts from count code 0 to count code 100 in one processing cycle. Further, the ranging range time is set to match the time corresponding to one processing cycle, that is, to match the time required for the counter 21 to count the count code 100.

As described above, the measuring device 11 is configured to perform pulse modulation in which the firing timing at which pulses are fired is changed every processing cycle according to the firing delay value. Therefore, in the example shown in FIG. 4, in processing cycle #1, a pulse is emitted with a firing delay value of 20 from the start of the processing cycle, and in processing cycle #2, a pulse is emitted with a firing delay value of 10 from the start of the processing cycle; In cycle #3, pulses are emitted with an emission delay value of 30 from the start of the processing cycle.

Accordingly, the ranging range time corresponding to the pulse emitted with the emission delay value 20 of the processing cycle #1 is from the count code 20 of the processing cycle #1 to the count code 20 of the processing cycle #2. Further, the ranging range time corresponding to the pulse emitted with the firing delay value 10 in the processing cycle #2 is from the count code 10 in the processing cycle #2 to the count code 10 in the processing cycle #3. At this time, the ranging range time corresponding to the pulse emitted with a firing delay value of 20 in processing cycle #1 and the ranging range time corresponding to the pulse emitted with a firing delay value of 10 in processing cycle #2 are as follows. There will be overlap between count code 10 and count code 20 in processing cycle #2.

First, case 1 (TDCout case 1) of the count code output from the TDC 15 shown in FIG. 4 will be explained. For example, in case 1, count code 25 is output in processing cycle #1, count code 15 is output in processing cycle #2, and count code 35 is output in processing cycle #3.

Therefore, if the reflected light detected by the count code 25 of processing cycle #1 is the reflected pulse emitted with the launch delay value 20 of processing cycle #1, then the launch delay value 20 is determined from the count code 25. ToF value 5 is obtained by subtracting . Similarly, if the reflected light detected at count code 15 in processing cycle #2 is a reflected pulse emitted at launch delay value 10 in processing cycle #2, then the launch delay value is determined from count code 15. A ToF value of 5 is obtained by subtracting 10. Furthermore, if the reflected light detected by the count code 35 in the processing cycle #3 is a pulse emitted with the launch delay value 30 in the processing cycle #3, then the launch delay value 30 is determined from the count code 35. ToF value 5 is obtained by subtracting .

Thereafter, similar processing cycles are repeated, and when a histogram of ToF values obtained in these processing cycles is generated, a ToF value of 5 shows a peak.

By the way, the reflected light detected by the count code 15 in the processing cycle #2 has a ranging range time corresponding to the pulse emitted with the firing delay value 20 in the processing cycle #1 and a firing delay value 10 in the processing cycle #2. The distance measurement range time corresponding to the pulse emitted in the range overlaps. Therefore, it is not possible to determine which distance measurement range time should be applied.

For example, when applying the ranging range time to a pulse emitted with a firing delay value of 20 in processing cycle #1, a count code of 15 in processing cycle #2 will become a count code of 115 if counting continues from the start of processing cycle #1. Corresponding to this, a ToF value of 95 is obtained by subtracting the firing delay value of 20 for processing cycle #1.

However, since the measurement device 11 performs pulse modulation as described above, the ghost ToF value 95 does not show a constant value like the true ToF value 5, and the launch delay value is changed every processing cycle. Scattered and distributed as changes occur. Note that at this time, there is no change in noise.

In this way, the measuring device 11 can suppress the negative effects caused by determining the ToF value of the ghost by scattering the ToF value of the ghost, and generate a histogram in which the true ToF value peaks in a shorter time. can do. Therefore, the measuring device 11 can shorten the time required to measure the distance to the object to be measured.

Further, case 2 (TDCout case 2) of the count code output from the TDC 15 shown in FIG. 4 will be explained. For example, in case 2, no count code is output in processing cycle #1, count code 60 is output in processing cycle #2, and count code 50 is output in processing cycle #3.

Therefore, if the reflected light detected by the count code 60 of processing cycle #2 is the reflected light of the pulse emitted with the firing delay value 20 of processing cycle #1, then the reflected light detected by the count code 60 of processing cycle #2 The ToF value 140 is obtained by subtracting the firing delay value 20 from the count code 160 from the start of processing cycle #1. Similarly, if the reflected light detected at the count code 50 of processing cycle #3 is the reflected pulse emitted at the firing delay value 10 of processing cycle #2, then the count code of processing cycle #3 ToF value 140 is obtained by subtracting the firing delay value 10 from 50 (count code 150 from the start of processing cycle #2).

After that, similar processing cycles are repeated, and when a histogram of ToF values obtained in these processing cycles is generated, a ToF value of 140 shows a peak.

By the way, if the reflected light detected by the count code 60 of the processing cycle #2 is the reflected light of the pulse emitted with the firing delay value 10 of the processing cycle #2, then the count code 60 of the processing cycle #2 ToF value 50 is obtained by subtracting firing delay value 10 from . Similarly, if the reflected light detected at the count code 50 of processing cycle #3 is a reflected pulse emitted at the firing delay value 30 of processing cycle #3, then the count code of processing cycle #3 The ToF value 20 is obtained by subtracting the firing delay value 30 from 50. However, these ToF values 50 and 20 are scattered as the pulse modulation described above is performed and the firing delay value changes every processing cycle, and they do not take a constant ToF value. . In other words, these ToF values 50 and 20 can be determined to be ghost ToF values.

In this way, the measuring device 11 can suppress the negative effects caused by determining the ToF value of the ghost by scattering the ToF value of the ghost, and generate a histogram in which the true ToF value peaks in a shorter time. can do. Therefore, the measuring device 11 can shorten the time required to measure the distance to the object to be measured.

In addition, in the measuring device 11, the ranging range time can be set to match the time corresponding to one processing cycle. For example, the time corresponding to one processing cycle can be set to be longer than the ranging range time. Compared to a configuration that requires setting (for example, providing overhead time), distance measurement can be performed in a shorter time.

Furthermore, with reference to FIG. 5, the effect of being able to perform distance measurement processing in the measuring device 11 using a laser beam that emits pulses two or more times within one processing cycle will be explained. .

For example, normally, a laser beam is output with one pulse emitted within one processing cycle. On the other hand, in the measuring device 11, it is possible to set the distance measuring range times overlappingly, and it is possible to output a laser beam in which the pulse is emitted twice or more within one processing cycle. can.

FIG. 5 shows an example of a laser beam in which pulses are emitted four times within one processing cycle. Further, a distance measuring range time corresponding to the processing cycle (100 counts) is set from the pulse emission timing.

In addition, in the example shown in FIG. 5, in processing cycle #1, the first pulse is emitted with a firing delay value of 20, the second pulse is fired with a firing delay value of 25, and the third pulse is fired with a firing delay value of 30. is fired, and the fourth pulse is fired with a firing delay value of 35. Similarly, in processing cycle #2, the first pulse is fired with a firing delay value of 10, the second pulse is fired with a firing delay value of 20, the third pulse is fired with a firing delay value of 69, and the firing delay The fourth pulse is emitted with a value of 77. In addition, in processing cycle #3, the first pulse is fired with a firing delay value of 7, the second pulse is fired with a firing delay value of 15, the third pulse is fired with a firing delay value of 22, and the firing delay value The fourth pulse was fired at 27.

On the other hand, the pulses of reflected light are detected by count code 80, count code 85, count code 90, and count code 95 of processing cycle #1. Similarly, pulses of reflected light are detected by count code 70 and count code 80 in processing cycle #2. Further, the pulses of the reflected light are detected by the count code 29, count code 37, count code 67, count code 75, and count code 82 of processing cycle #3.

Then, for each count code in which a pulse of reflected light is detected, the measurement device 11 subtracts each launch delay value, which is the timing at which a plurality of ranging range times including that count code are started, from that count code. Then, calculation is performed to obtain the ToF value.

For example, regarding the pulse of reflected light detected by the count code 80 of the processing cycle #1, the count code 80 of the processing cycle #1 is included in four ranging range times. Therefore, the firing delay values (20, 25, 30, 35), which are the timings at which the four ranging range times that include count code 80 of processing cycle #1 start, are subtracted from count code 80 of processing cycle #1. As a result, a ToF value of 60, a ToF value of 55, a ToF value of 50, and a ToF value of 45 are obtained.

Further, regarding the pulse of reflected light detected by the count code 70 of the processing cycle #2, the count code 70 of the processing cycle #2 is included in the three ranging range times. Therefore, the firing delay value (10, 20, 69), which is the timing at which the three ranging range times including count code 70 of processing cycle #2 are started, is subtracted from count code 70 of processing cycle #2. , ToF value 60, ToF value 50, and ToF value 1 are determined.

Further, regarding the pulse of reflected light detected by the count code 29 of the processing cycle #3, the count code 29 of the processing cycle #3 is included in the six ranging range times. Therefore, the firing delay value (69, 77 in processing cycle #2, 7, 15, 22, 27) from the count code 29 of processing cycle #3 (or the corresponding count code 129 of processing cycle #2), ToF value 22, ToF value 14, ToF value 7, ToF value 2, ToF value 60 , and ToF value 52 are determined.

Further, regarding the pulse of reflected light detected by the count code 75 of the processing cycle #3, the count code 75 of the processing cycle #3 is included in the five ranging range times. Therefore, the firing delay value (77 in processing cycle #2, 7, 15, 22, 27 in processing cycle #3) is the timing at which the five ranging range times that include count code 75 in processing cycle #3 start. is subtracted from the count code 75 in processing cycle #3 (or the corresponding count code 175 in processing cycle #2) to obtain ToF value 68, ToF value 60, ToF value 53, ToF value 48, and ToF value 98. Desired.

In this way, for each count code in which a pulse of reflected light is detected, each firing delay value, which is the timing at which multiple ranging range times that include that count code start, is subtracted from that count code. The ToF values shown include the true ToF value of 60. Further, ToF values other than the true ToF value 60 are scattered and distributed in accordance with changing the firing delay value for each processing cycle. Therefore, in the histogram generated from all the ToF values obtained by such calculation, the true ToF value of 60 will show the peak.

Therefore, even if the measuring device 11 outputs a laser beam that emits pulses twice or more in one processing cycle, the known firing delay value is subtracted from the count code in which each pulse is detected. The ToF value can be determined by performing calculations. As a result, the measuring device 11 can obtain more ToF values in a short time and identify the peak in the histogram, thereby reducing the time required for distance measurement processing.

With reference to FIG. 6, the effect of canceling the influence of DNL on measurement accuracy in the measurement device 11 will be described.

FIG. 6 shows an example of the configuration of a counter 21 that includes five flip-flop circuits and outputs a 32-value count code. Further, FIG. 6 shows a waveform representing a count code output from the counter 21, as well as DNL and INL (Integral Non-Linearity) components for each count. As shown in the figure, the DNL and INL components have the same magnitude for the same count code in each processing cycle.

Then, as described above, in the measuring device 11, a pulse is emitted at a timing delayed from the start of the processing cycle (emission ToF) according to a different emission delay value for each processing cycle. Therefore, the timing at which the pulse of reflected light is detected (the timing indicated by the tip of the white arrow in FIG. 6) also differs for each processing cycle, and the count code taken into the latch 22 at each timing also differs. becomes. As a result, the DNL components included in the count code for each processing cycle are different, so that the influence of DNL on distance measurement accuracy can be canceled.

For example, when a pulse is emitted at the timing when a processing cycle starts, as in the conventional case, the timing at which a pulse of reflected light is detected is the same regardless of the processing cycle, and the count is taken into the latch 22 at that timing. The code will also be the same. Therefore, in the past, the DNL component included in the count code for each processing cycle directly affected the distance measurement accuracy.

On the other hand, in the measuring device 11, the DNL components included in the count code for each measurement cycle are different, and these components are averaged, so the direct influence of DNL on measurement accuracy is reduced. It will be cancelled. Therefore, the measuring device 11 can further improve measurement accuracy.

Furthermore, as shown in FIG. 7, by configuring the upper bits and lower bits to be separated, the influence of DNL on measurement accuracy can be canceled more reliably.

FIG. 7 shows an example in which a high-order 1-bit counter is provided in addition to the waveform representing the count code shown in FIG. That is, by adding one high-order bit to a 32-value count code (lower bit), a 64-value count code can be expressed.

For example, since the transition position of the counter affects the DNL cycle, by configuring the upper digits independently of the transition position, two 32-value DNL cycles will appear within a 64-value processing cycle. For example, the upper digits can be configured by providing redundant bits or by direct counting with the latch 22.

In this way, by performing pulse modulation for 32 values within a 64-value processing cycle, it is possible to achieve averaging of DNL, and the influence of DNL on measurement accuracy is more reliably canceled. Therefore, the measuring device 11 can further improve measurement accuracy.

The effect of suppressing the influence of noise caused by disturbance radio waves synchronized with the processing cycle will be described with reference to FIGS. 8 to 11.

For example, as shown in Figure 8, when the disturbance radio wave is synchronized with the processing cycle (frequency of disturbance radio wave = 1/processing cycle), the count is modulated by using the disturbance radio wave as a standing wave, and the disturbance radio wave Pseudo peaks may occur in the histogram due to the influence of noise. Therefore, in this case, if pulses are emitted at a fixed emission timing every processing cycle without pulse modulation, the pseudo peak will be higher than the peak of the count code that indicates the timing at which the reflected wave pulse is received. It may be affected like this.

On the other hand, as shown on the left side of FIG. 9, if pulses are emitted at different emission timings for each processing cycle by pulse modulation, the ranging range time will start at different timings according to each emission timing. For this reason, even if the disturbance radio waves are synchronized with the processing cycle, the pseudo peaks that occur in the histogram will shift due to the influence of noise caused by the disturbance radio waves for each ranging range time.

Therefore, by performing full-range pulse modulation that changes the pulse emission timing over the entire processing period and adding together the histograms of different ranging range times, the influence of the disturbance radio waves can be completely averaged out, as shown on the right side of Figure 9. can be used to eliminate pseudo peaks. In other words, only the count code that indicates the timing at which the pulse of the reflected wave of the laser beam reflected by the object to be measured remains as a peak.

For example, in the measuring device 11, when there is a disturbance radio wave synchronized with a processing cycle, the timing instruction section 16 is activated through electromagnetic induction by the disturbance radio wave, and a pulse is generated to emit a pulse at a different emission timing for each processing cycle. Modulation may also be performed.

Note that if full-area pulse modulation is not performed, the influence of disturbance radio waves will not be completely averaged out. In other words, as shown in FIG. 10, if the range in which the pulse emission timing is changed (LT modulation range) is narrower than the processing cycle without changing the pulse emission timing over the entire processing cycle, each pulse Starting from , averaging is performed by integration (moving average) over a range in which the pulse emission timing is changed. Therefore, in order to completely average out the influence of disturbance radio waves and eliminate pseudo peaks, it is desirable to perform full-range pulse modulation.

In addition, if full range pulse modulation cannot be performed, as shown in FIG. 11, by changing the maximum value of the count code counted by the counter 21 in any processing cycle, the influence of disturbance radio waves synchronized with the processing cycle can be adjusted. can be suppressed. That is, as the maximum value of the count code counted by the counter 21 is changed, the timing of the processing cycle is changed, and by shifting the phase of the processing cycle from the disturbance radio wave, the influence of the disturbance radio wave is suppressed. That will happen. In this case, as shown in FIG. 11, the maximum value of the count code may be changed to lengthen the processing cycle, or conversely, the maximum value of the count code may be changed to shorten the processing cycle. .

In this way, the measuring device 11 can suppress the influence of noise caused by disturbance radio waves synchronized with the processing cycle, and can accurately generate a histogram in which the count code indicating the timing at which the pulse of the reflected wave is received has a peak. can do. Thereby, the measuring device 11 can further improve measurement accuracy.

FIG. 12 is a diagram illustrating the effect of being able to shift the ranging range time depending on which firing timing is used as the starting point.

Similar to FIG. 4, FIG. 12 shows processing cycles #1 to #3 that are repeated in a circular manner. Then, in processing cycle #1, a pulse is emitted with a firing delay value of 20 from the start of the processing cycle, in processing cycle #2, a pulse is emitted with a firing delay value of 10 from the start of the processing cycle, and in processing cycle #3, a pulse is emitted with a firing delay value of 10 from the start of the processing cycle. Pulses are being emitted with a firing delay value of 30 from the start. Further, the count code is not output in the processing cycle #1, the count code 60 is output in the processing cycle #2, and the count code 50 is output in the processing cycle #3.

At this time, a ToF value of 50 is determined for the pulse of reflected light detected by the count code 60 of the processing cycle #2, using the firing delay value 10 of the processing cycle #2 as the starting point. Further, for the pulse of the reflected light detected by the count code 50 of the processing cycle #3, a ToF value of 20 is determined using the firing delay value 30 of the processing cycle #3 as the starting point. Therefore, if such firing timing is used as a starting point, these ToF values of 50 and ToF values of 20 can be determined to be ghosts.

On the other hand, for the pulse of the reflected light detected by the count code 60 in the processing cycle #2, a ToF value of 140 is determined using the firing delay value 20 in the processing cycle #1 as the starting point. Further, for the pulse of the reflected light detected by the count code 50 in the processing cycle #3, a ToF value of 140 is determined using the firing delay value 10 in the processing cycle #2 as the starting point. Therefore, since a constant ToF value can be obtained using such a firing timing as a starting point, it is possible to shift the ranging range time using the firing timing at which this ToF value of 140 is obtained as a starting point.

In this way, the measuring device 11 can shift the ranging range time to the firing timing that is the starting point of the ranging range time at which a constant ToF value can be obtained.

As described above, the measuring device 11 can measure the distance to the object to be measured with high accuracy in a shorter time, as described with reference to FIGS. 4 to 12.

In addition, in this embodiment, as shown in A of FIG. 13, explanation was given using a ramp waveform in which the count-up is repeated for each processing cycle, but in addition to this, the ramp waveform is used in which the count is cycled without stopping. A ramp waveform may also be used.

For example, as shown in FIG. 13B, a ramp waveform that repeats the countdown every processing cycle, or as shown in FIG. A ramp waveform or the like can be used. Furthermore, as shown in FIG. 13D, a ramp waveform may be used in which counting does not stop during all processing cycles, but there is a counting stop section during a certain processing cycle. Alternatively, a multi-slope ramp waveform as shown in E in FIG. 13 (in the example shown in E in FIG. 13, a ramp waveform that cycles continuously by combining two waveforms) may be used.

<Fire delay value of predetermined pattern>
As described above, the measurement device 11 can vary the firing delay value for each processing cycle by performing pulse modulation, and for example, can set the firing delay value to be random. Alternatively, the measuring device 11 may be set so that the firing delay value is shifted in a predetermined pattern every processing cycle.

Therefore, a processing example in which the firing delay value is shifted in a predetermined pattern every processing cycle will be described with reference to FIGS. 14 to 19.

FIG. 14 shows an example in which four pulses are emitted at emission timings that are shifted at equal intervals (predetermined pattern) with respect to the preprocessing period.

In this way, by shifting the light emission timing at equal intervals, the out-of-range ToF caused by light emission in the preprocessing cycle (the ToF value of ghosts caused by pulses of reflected light detected outside the ranging range time) can be reduced. , when a histogram is generated, the values are accumulated at equal intervals. Therefore, in the measuring device 11, by performing histogram processing based on the equal intervals (predetermined pattern), it is possible to predict the shape of the out-of-range ToF and perform filtering or the like.

A method of controlling laser irradiation timing and a method of processing TOF results will be described with reference to FIG. 15.

FIG. 15 shows an example of a pattern in which the firing delay value DLY1 and the firing delay value DLY2 are alternately changed. That is, the timing instruction unit 16 supplies the firing delay value to the firing timing signal generating unit 12 so as to shift the emission timing of the pulse in a pattern in which the firing delay value DLY1 and the firing delay value DLY2 alternate. Then, the calculation unit 17 performs an operation of alternately subtracting the firing delay value DLY1 and the firing delay value DLY2 supplied from the timing instruction unit 16 from the count code supplied from the latch 22 of the TDC 15, and calculates by this operation. The calculated ToF value is supplied to the histogram generation section 18.

In accordance with such a pattern, the histogram generated by the histogram generation unit 18 has two peaks as shown in the figure depending on the out-of-range ToF. That is, if it is within the range, one peak will occur in the histogram shape, whereas if it is outside the range, two peaks will occur. Note that the lower side of FIG. 15 shows a more realistic histogram shape.

In the example shown here, the histogram generation unit 18 can predict that the two peaks that are twice the launch delay value are histogram shapes due to out-of-range ToF, and extract the histogram of out-of-range ToF based on this prediction. be able to.

Furthermore, in the measuring device 11, the histogram generation unit 18 can perform arithmetic processing on the histogram of the out-of-range ToF. For example, the histogram generation unit 18 performs calculation processing to separately obtain the center of gravity of the histogram shape due to the out-of-range ToF, calculation processing to remove a portion due to the out-of-range ToF, calculation processing to manipulate the center of gravity of the histogram shape due to the out-of-range ToF ( For example, operations such as moving the center of gravity to a non-ROI can be performed. Of course, the histogram generation unit 18 may employ calculation processing other than these.

FIG. 16 is a flowchart illustrating a process in which the firing delay value is shifted in a predetermined pattern every processing cycle.

In step S21, the timing instruction unit 16 supplies the firing timing signal generating unit 12 with a firing delay value that changes the pulse emission timing in a predetermined pattern (for example, an alternating pattern as shown in FIG. 15). . As a result, the firing timing signal generation unit 12 generates a Tx pulse signal in which the firing timing is delayed from the timing to start the processing cycle according to the firing delay value, and the laser driver 13 generates a pulsed pulse signal according to the Tx pulse signal. Outputs laser light.

In step S22, when the histogram generation unit 18 generates a histogram of the ToF values supplied from the calculation unit 17, the histogram shape of the out-of-range ToF (for example, , two peaks as shown in FIG. 15).

In step S23, the histogram generation unit 18 extracts (filters) the histogram of the out-of-range ToF from the histogram shape of the out-of-range ToF predicted in step S22.

In step S24, the histogram generation unit 18 performs various calculation processes as described above on the out-of-range ToF histogram extracted in step S23, and then the process ends.

Similar to FIG. 6 described above, FIG. 17 is a diagram illustrating the effect of canceling the influence of DNL on measurement accuracy when the firing delay value is shifted in a predetermined pattern for each processing cycle.

As shown in FIG. 17, the same DNL and INL appear repeatedly, and INL=0 at each repetition period. Then, by performing pulse modulation, the same ToF value is obtained from different count codes output from the TDC 15. That is, even though the same ToF value is obtained, the influence of the outputs of the TDCs 15 having different DNLs can be dispersed.

Note that in FIG. 17, the time difference between edges of the counter 21 is LSB, and the time error is DNL. Further, INL is 0 in the repetition period (32 LSB) of the lower counter, and the average of 32 DNLs becomes 0 depending on the pulse emission timing. In this way, it is necessary to change the firing timing in order to average the DNL, and by shifting the firing delay value of the firing timing in a predetermined pattern, we can minimize the shape of the ghost histogram due to the influence of out-of-range ToF. You can prevent this from happening.

Here, with reference to FIGS. 18 and 19, the relationship between the delay in laser irradiation timing and DNL, and the shape of the ghost histogram due to the influence of the out-of-range ToF will be described. Note that in FIGS. 18 and 19, averaging of 5 bins (in FIG. 17, averaging of 32 bins) is illustrated for the sake of simplification of explanation.

FIG. 18 shows a first example in which the firing delay value is shifted in a pattern such that it increases by 1 every processing period from 10 to 14 and then decreases by 1 every processing period from 14 to 10. There is.

If the firing delay value is shifted in such a pattern, the difference between the Nth and N+1st irradiations of out-of-range ToF, the difference between the N+1st and N+2nd irradiations of out-of-range ToF, and the difference between the N+2nd and N+3 irradiations of out-of-range ToF. The difference from the irradiation time and the difference between the N+3rd and N+4th irradiation of out-of-range ToF are -1, respectively. Furthermore, the difference between the N+4th and N+5th out-of-range ToF irradiations is 0. Furthermore, the difference between the N+5th and N+6th irradiation of the out-of-range ToF, the difference between the N+6th and N+7th irradiation of the out-of-range ToF, the difference between the N+7th and N+8th irradiation of the out-of-range ToF, and the difference between the out-of-range ToF irradiation N+7th and N+8th, The difference between the N+8th irradiation and the N+9th irradiation is +1.

Therefore, as shown in the figure, two peaks of −1 and +1 occur, and the histogram shape becomes low at 0, which is the median value of the out-of-range ToF. Note that if the firing delay value is not changed, the histogram will have a peak shape as shown by the broken line.

FIG. 19 shows a second example in which the firing delay value is shifted in a pattern such that it increases by 1 every 3 processing cycles from 10 to 14 and then decreases by 1 every 3 processing cycles from 14 to 10. There is.

If the firing delay value is shifted in such a pattern, the difference between the N+2nd and N+3rd irradiation of out-of-range ToF, the difference between the N+5th and N+6th irradiation of out-of-range ToF, and the difference between the N+8th and N+9th irradiation of out-of-range ToF. The difference from the irradiation time and the difference between the N+11th and N+12th irradiation of out-of-range ToF are -1, respectively. Also, the difference between the N+18th and N+19th irradiation of out-of-range ToF, the difference between the N+21st and N+22nd irradiation of out-of-range ToF, the difference between the N+24th and N+25th irradiation of out-of-range ToF, and the difference between out-of-range ToF irradiation N+24th and N+25th. The difference between the N+27th irradiation and the N+28th irradiation is +1. In other cases, it becomes 0.

Therefore, as shown in the figure, the histogram shape becomes such that the frequency of changing the firing delay value decreases, and the frequency of a specific ToF value increases. Note that if the firing delay value is not changed, the histogram will have a peak shape as shown by the broken line. That is, the increase or decrease in the height of 0, which is the median value of the out-of-range ToF, can be controlled by changing the frequency of changing the firing delay value.

In this way, by shifting the firing delay value of the firing timing in a predetermined pattern, it is possible to prevent the shape of the ghost histogram from changing due to the influence of the out-of-range ToF as much as possible. For example, if the firing delay value of the firing timing is randomly shifted, the histogram shape will not be obtained because the firing timing will be dispersed.

<Computer configuration example>
Next, the series of processes (measuring method) described above can be performed by hardware or software. When a series of processes is performed using software, the programs that make up the software are installed on a general-purpose computer or the like.

FIG. 20 is a block diagram showing a configuration example of an embodiment of a computer in which a program that executes the series of processes described above is installed.

The program can be recorded in advance on the hard disk 105 or ROM 103 as a recording medium built into the computer.

Alternatively, the program can be stored (recorded) in a removable recording medium 111 driven by the drive 109. Such a removable recording medium 111 can be provided as so-called package software. Here, examples of the removable recording medium 111 include a flexible disk, a CD-ROM (Compact Disc Read Only Memory), an MO (Magneto Optical) disk, a DVD (Digital Versatile Disc), a magnetic disk, and a semiconductor memory.

In addition to installing the program on the computer from the removable recording medium 111 as described above, the program can also be downloaded to the computer via a communication network or broadcasting network and installed on the built-in hard disk 105. In other words, a program can be transferred wirelessly from a download site to a computer via an artificial satellite for digital satellite broadcasting, or transferred by wire to a computer via a network such as a LAN (Local Area Network) or the Internet. be able to.

The computer has a built-in CPU (Central Processing Unit) 102, and an input/output interface 110 is connected to the CPU 102 via a bus 101.

The CPU 102 executes a program stored in a ROM (Read Only Memory) 103 when a command is input by the user through the input/output interface 110 by operating the input unit 107 or the like. . Alternatively, the CPU 102 loads a program stored in the hard disk 105 into the RAM (Random Access Memory) 104 and executes the program.

Thereby, the CPU 102 performs processing according to the flowchart described above or processing performed according to the configuration of the block diagram described above. Then, the CPU 102 outputs the processing result from the output unit 106 or transmits it from the communication unit 108 via the input/output interface 110, or records it on the hard disk 105, as necessary.

Note that the input unit 107 includes a keyboard, a mouse, a microphone, and the like. Further, the output unit 106 is configured with an LCD (Liquid Crystal Display), a speaker, and the like.

Here, in this specification, the processing that a computer performs according to a program does not necessarily need to be performed in chronological order in the order described as a flowchart. That is, the processing that a computer performs according to a program includes processing that is performed in parallel or individually (for example, parallel processing or processing using objects).

Furthermore, the program may be processed by one computer (processor) or may be distributed and processed by multiple computers. Furthermore, the program may be transferred to a remote computer and executed.

Furthermore, in this specification, a system refers to a collection of multiple components (devices, modules (components), etc.), regardless of whether all the components are located in the same casing. Therefore, multiple devices housed in separate casings and connected via a network, and a single device with multiple modules housed in one casing are both systems. .

Furthermore, for example, the configuration described as one device (or processing section) may be divided and configured as a plurality of devices (or processing sections). Conversely, the configurations described above as a plurality of devices (or processing units) may be configured as one device (or processing unit). Furthermore, it is of course possible to add configurations other than those described above to the configuration of each device (or each processing section). Furthermore, part of the configuration of one device (or processing unit) may be included in the configuration of another device (or other processing unit) as long as the configuration and operation of the entire system are substantially the same. .

Further, for example, the present technology can take a cloud computing configuration in which one function is shared and jointly processed by a plurality of devices via a network.

Furthermore, for example, the above-described program can be executed on any device. In that case, it is only necessary that the device has the necessary functions (functional blocks, etc.) and can obtain the necessary information.

Further, for example, each step explained in the above flowchart can be executed by one device or can be shared and executed by a plurality of devices. Furthermore, when one step includes multiple processes, the multiple processes included in that one step can be executed by one device or can be shared and executed by multiple devices. In other words, multiple processes included in one step can be executed as multiple steps. Conversely, processes described as multiple steps can also be executed together as one step.

Note that in a program executed by a computer, the processing of the steps described in the program may be executed in chronological order according to the order described in this specification, in parallel, or in a manner in which calls are made. It may also be configured to be executed individually at necessary timings such as at certain times. In other words, the processing of each step may be executed in a different order from the order described above, unless a contradiction occurs. Furthermore, the processing of the step of writing this program may be executed in parallel with the processing of other programs, or may be executed in combination with the processing of other programs.

It should be noted that the plurality of techniques described in this specification can be implemented independently, unless a contradiction occurs. Of course, it is also possible to implement any plurality of the present techniques in combination. For example, part or all of the present technology described in any embodiment can be implemented in combination with part or all of the present technology described in other embodiments. Furthermore, part or all of any of the present techniques described above can be implemented in combination with other techniques not described above.

<Example of configuration combinations>
Note that the present technology can also have the following configuration.
(1)
a firing timing signal generation unit that repeatedly generates a signal instructing firing timing for firing pulses of laser light at each predetermined processing cycle;
a counter that continuously counts a count code indicating the timing of receiving a pulse in the reflected light that is reflected by the laser beam and returned from the object to be measured at the time of switching of the processing cycle;
and a timing instruction unit that instructs the firing timing signal generation unit to set a firing delay value indicating a time by which the firing timing is delayed from the start of the processing cycle to be different for each processing cycle.
(2)
Subtracting the launch delay value instructed by the timing instruction section from the count code indicating the timing at which the pulse in the reflected light is received, and measuring the flight time for the light to travel back and forth between the object and the object to be measured. The measuring device according to (1) above, further comprising a calculation unit that calculates a measured value corresponding to the measured value.
(3)
a histogram generation unit that generates a histogram of the measured values obtained by the calculation unit each time the processing cycle is repeated, and causes the processing cycle to be repeatedly performed until the measurement value that shows a peak in the histogram is identified; The measuring device according to (2) above, further comprising:
(4)
Distance measurement, which is the width of the flight time for light to travel back and forth between the distance measurement range that represents a certain range of distance that includes the distance to the object to be measured. The measuring device according to (2) above, wherein the range time is made to coincide with the time of the processing cycle, and the ranging range time is started from the firing timing delayed from the start of the processing cycle.
(5)
The emission timing signal generation unit outputs the laser light such that the number of pulse emission is two or more times within one processing cycle,
For each of the count codes in which the pulses of the reflected light are detected, the calculation unit calculates each of the launch delay values, which are the timings at which the plurality of ranging range times including the count codes are started, based on the count code. The measuring device according to (4) above, wherein the measuring device performs an operation to obtain the measured value by subtracting from .
(6)
The measuring device according to any one of (1) to (5) above, wherein a count code counted by the counter is a lower bit, and a configuration is provided in which the upper bit is counted separately from the count by the counter.
(7)
The measuring device according to any one of (1) to (6) above, wherein the timing instruction section changes the emission timing of the laser beam pulse over the entire processing period.
(8)
The measuring device according to any one of (1) to (7), wherein the counter changes the length of the processing cycle by changing the maximum value of the count code in any of the processing cycles.
(9)
The measuring device according to (4) above, wherein the ranging range time is shifted to the firing timing, which is the starting point of the ranging range time for which the constant measurement value is calculated.
(10)
The measuring device according to (3) above, wherein the timing instruction unit changes the firing delay value so as to change randomly every processing cycle.
(11)
The measuring device according to (3) above, wherein the timing instruction unit changes the firing delay value so as to change in a predetermined pattern every processing cycle.
(12)
When the distance to the distance measurement target is the distance measurement target, the distance measurement range is the width of the flight time for light to travel back and forth between the distance measurement range that represents a certain range of distance that includes that distance. time and
The histogram generation unit predicts a histogram shape of a measured value of a ghost caused by a pulse of reflected light detected outside the ranging range time based on a predetermined pattern in which the launch delay value changes, and The measuring device according to (11) above, which extracts a histogram shape of a ghost measurement value.
(13)
The measuring device according to (12), wherein the histogram generation unit performs predetermined calculation processing on the histogram shape of the measured value of the ghost.
(14)
The measuring device is
Repeating every predetermined processing cycle to generate a signal instructing the timing of emitting a pulse of laser light;
Continuing to count a count code indicating the timing of receiving a pulse in the reflected light that is reflected by the laser beam and returned from the object to be measured at the time of switching of the processing cycle;
A measuring method comprising: instructing a firing delay value indicating a time to delay the firing timing from the start of the processing cycle to be different for each processing cycle.
(15)
In the computer of the measuring device,
Repeating every predetermined processing cycle to generate a signal instructing the timing of emitting a pulse of laser light;
Continuing to count a count code indicating the timing of receiving a pulse in the reflected light that is reflected by the laser beam and returned from the object to be measured at the time of switching of the processing cycle;
A program for executing measurement processing, the program comprising: instructing a firing delay value indicating a time by which the firing timing is delayed from the start of the processing cycle to be different for each processing cycle.

Note that this embodiment is not limited to the embodiment described above, and various changes can be made without departing from the gist of the present disclosure. Moreover, the effects described in this specification are merely examples and are not limited, and other effects may also be present.

11 measurement device, 12 emission timing signal generation section, 13 laser driver, 14 light receiving element, 15 TDC, 16 timing instruction section, 17 calculation section, 18 histogram generation section, 19 distance calculation section, 21 counter, 22 latch

Claims (15)

a firing timing signal generation unit that repeatedly generates a signal instructing firing timing for firing pulses of laser light at each predetermined processing cycle;
a counter that continuously counts a count code indicating the timing of receiving a pulse in the reflected light that is reflected by the laser beam and returned from the object to be measured at the time of switching of the processing cycle;
and a timing instruction unit that instructs the firing timing signal generation unit to set a firing delay value indicating a time by which the firing timing is delayed from the start of the processing cycle to be different for each processing cycle. Subtracting the launch delay value instructed by the timing instruction section from the count code indicating the timing at which the pulse in the reflected light is received, and measuring the flight time for the light to travel back and forth between the object and the object to be measured. The measuring device according to claim 1, further comprising a calculation unit that calculates a measured value corresponding to the measured value. a histogram generation unit that generates a histogram of the measured values obtained by the calculation unit each time the processing cycle is repeated, and causes the processing cycle to be repeatedly performed until the measurement value that shows a peak in the histogram is identified; The measuring device according to claim 2, further comprising: Distance measurement, which is the width of the flight time for light to travel back and forth between the distance measurement range that represents a certain range of distance that includes the distance to the object to be measured. The measuring device according to claim 2, wherein the range time is made to coincide with the time of the processing cycle, and the ranging range time is started from the firing timing delayed from the start of the processing cycle. The emission timing signal generation unit outputs the laser light such that the number of pulse emission is two or more times within one processing cycle,
For each of the count codes in which the pulses of the reflected light are detected, the calculation unit calculates each of the launch delay values, which are the timings at which the plurality of ranging range times including the count codes are started, based on the count code. The measuring device according to claim 4, wherein the measuring device performs an operation to obtain the measured value by subtracting from . The measuring device according to claim 1, further comprising a configuration in which a count code counted by the counter is used as lower bits, and higher bits are counted separately from counting by the counter. The measuring device according to claim 1, wherein the timing instruction section changes the emission timing of the laser beam pulse throughout the processing cycle. The measuring device according to claim 1, wherein the counter changes the length of the processing cycle by changing the maximum value of the count code in any of the processing cycles. The measuring device according to claim 4, wherein the ranging range time is shifted to the firing timing, which is the starting point of the ranging range time for which the constant measurement value is calculated. The measuring device according to claim 3, wherein the timing instruction section changes the firing delay value so that it changes randomly for each processing cycle. The measuring device according to claim 3, wherein the timing instruction unit changes the firing delay value so as to change in a predetermined pattern every processing cycle. When the distance to the distance measurement target is the distance measurement target, the distance measurement range is the width of the flight time for light to travel back and forth between the distance measurement range that represents a certain range of distance that includes that distance. time and
The histogram generation unit predicts a histogram shape of a measured value of a ghost caused by a pulse of reflected light detected outside the ranging range time based on a predetermined pattern in which the launch delay value changes, and The measuring device according to claim 11, wherein a histogram shape of a measured value of a ghost is extracted. The measuring device according to claim 12, wherein the histogram generation unit performs predetermined calculation processing on a histogram shape of the measured value of the ghost. The measuring device is
Repeating every predetermined processing cycle to generate a signal instructing the timing of emitting a pulse of laser light;
Continuing to count a count code indicating the timing of receiving a pulse in the reflected light that is reflected by the laser beam and returned from the object to be measured at the time of switching of the processing cycle;
A measuring method comprising: instructing a firing delay value indicating a time to delay the firing timing from the start of the processing cycle to be different for each processing cycle. In the computer of the measuring device,
Repeating every predetermined processing cycle to generate a signal instructing the timing of emitting a pulse of laser light;
Continuing to count a count code indicating the timing of receiving a pulse in the reflected light that is reflected by the laser beam and returned from the object to be measured at the time of switching of the processing cycle;
A program for executing measurement processing, the program comprising: instructing a firing delay value indicating a time by which the firing timing is delayed from the start of the processing cycle to be different for each processing cycle.

Images