JP2012251862A - Laser radar apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser radar apparatus having high distance measuring accuracy and a wide measurable distance interval without requiring a distance measuring device other than the laser radar apparatus.SOLUTION: The laser radar apparatus includes: a light transmitting/receiving part 10 for oscillating a laser beam to an object, receiving reflected light from the object and converting the received reflected light into a reception signal; a distance and intensity calculation part 20 for calculating a distance signal indicating a distance up to an irradiation point of the laser beam by measuring time required from the oscillation of the laser beam from the light transmitting/receiving part 10 up to the reception of the reflected light on the basis of a previously set measurable time interval and calculating an intensity signal indicating the reflected light intensity of the laser beam from the irradiation point of the laser beam; and a signal processing part 30 for setting a measurable time interval narrower than the previously set measurable time interval on the basis of the distance signal and the intensity signal calculated by the distance and intensity calculation part 20. The distance and intensity calculation part 20 calculates the distance signal on the basis of the narrow measurable time interval set by the signal processing part 30.

Description

  The present invention relates to a laser radar apparatus using a laser distance measurement method for deriving a distance to a target from a difference between an oscillation time of laser light and a light reception time of reflected light.

  A conventional laser radar device has a time standard as a reference for time measurement. Based on the time standard, the reflected light feedback time, which is the time interval from the laser light oscillation time to the reflected light receiving time, is measured. The distance value to the target was calculated from the reflected light feedback time and the light velocity.

  FIG. 12 is a configuration diagram of a time measurement unit that measures the difference between the laser beam transmission time and the reflected light reception time in the laser radar device. The time measuring unit shown in FIG. 12 has a lamp voltage using a constant current source as a time standard. The lamp voltage starts to increase when the constant current source is switched on by a gate signal which is a reference for the oscillation time of the laser beam, and increases in proportion to the time according to the current value of the constant current source. When a reception signal is generated due to reception of the reflected light, an S / H trigger is output by the peak detection circuit. The S / H trigger reads the instantaneous voltage value of the lamp voltage by the S / H circuit and outputs it as a hold voltage value. Thereafter, the input of the gate signal is stopped, the reset signal is input, and the lamp voltage is discharged. The reflected light feedback time is calculated from the proportionality constant to the time of the gate signal and the lamp voltage and the hold voltage value.

  Since constant noise exists in the constant current source, noise also exists in the lamp voltage, and the hold voltage value has an error with respect to the timing of the S / H trigger. Since the hold voltage value has an error, the calculated reflected light feedback time also has an error.

  Here, when the proportionality constant of the lamp voltage is increased, the hold voltage change amount with respect to time is increased. On the other hand, the error of the hold voltage value is a constant value, so that the error of the relatively calculated reflected light feedback time is reduced. Conversely, when the proportional constant of the lamp voltage is reduced, the error of the reflected light feedback time calculated relatively increases. The error of the reflected light feedback time calculated by increasing the proportional constant of the lamp voltage is reduced, but since the lamp voltage value has an upper limit, the measurable time interval is shortened. Conversely, if the proportional constant of the lamp voltage is reduced, the error increases, but the measurable time interval can be increased.

  Therefore, the longer the measurable time interval of the reflected light feedback time, the worse the time measuring accuracy, and the shorter the measurable time interval, the better the time measuring accuracy.

  Similarly, the distance measurement error is inversely proportional to the measurable distance interval. When measuring a wide distance interval, the distance measurement accuracy is coarse, and when measuring a narrow distance interval, the accuracy is fine. As a result, both the measurable distance interval and the distance measurement accuracy cannot be increased, and are in a trade-off relationship.

  As a conventional technique for solving this problem, for example, Patent Document 1 proposes an apparatus having both a laser radar apparatus and another distance measurement method. The present invention is an apparatus in which a target is roughly detected by another distance measuring method having a wide measurable distance interval, and a target is precisely detected by a laser radar apparatus having high distance measurement accuracy using the result of the rough detection.

JP 2007-240276 A

  However, an apparatus having both a laser radar apparatus and another distance measuring method as in Patent Document 1 must include another distance measuring apparatus in addition to the laser radar apparatus, and the apparatus becomes large and the number of parts increases. There was a problem that it would end up.

  The present invention has been made to solve such a problem, and provides a laser radar device having high distance measurement accuracy and a wide measurable distance interval without providing any other distance measurement device other than the laser radar device. For the purpose.

  In order to achieve the above object, a laser radar device according to the present invention includes a transmission / reception unit configured to oscillate laser light toward a target, receive reflected light from the target, and convert the received light into a received signal. Based on the measurable time interval, the distance signal indicating the distance to the laser beam irradiation point is calculated by measuring the time from the oscillation of the laser beam by the transmitter / receiver to the reception of the reflected light, and from the laser beam irradiation point A distance intensity calculation unit that calculates an intensity signal indicating the reflected light intensity of the laser beam, and a measurable time interval that is narrower than a measurable time interval preset based on the distance signal and the intensity signal calculated by the distance intensity calculation unit. A distance processing unit that calculates a distance signal based on the narrow measurable time interval set by the signal processing unit.

  According to the laser radar device of the present invention, the distance to the target is measured a plurality of times, the measurable distance interval is set wide in the initial measurement, and the target is detected with low accuracy. In order to detect the target with high accuracy by resetting the measurable distance interval narrowly using the result, it has both high distance measurement accuracy and a wide measurable distance interval without providing any other distance measuring device other than the laser radar device. be able to.

1 is an overall configuration of a laser radar apparatus according to Embodiment 1 of the present invention. It is the graph which showed the lamp voltage at the time of the first measurement of the laser radar apparatus which concerns on Embodiment 1 of this invention. It is the graph shown about the reset of the initial measurement of the laser radar apparatus which concerns on Embodiment 1 of this invention, and a measurable distance interval. It is the graph shown about the lamp voltage at the time of the next measurement of the laser radar apparatus which concerns on Embodiment 1 of this invention. It is a flowchart of the process sequence of the laser radar apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the time change of the lamp voltage of the time measurement part in the laser radar apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the time change of the lamp voltage when the intensity | strength of the signal which the target intensity data of the laser radar apparatus which concerns on Embodiment 1 of this invention shows is high, and the intensity | strength of a signal is low. FIG. 2 is a diagram illustrating a configuration in a case where the center of a reception field of view and a laser beam propagation direction are not coaxial in the overall configuration of the laser radar apparatus of FIG. It is the whole structure of the laser radar apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the time change of the lamp voltage of the laser radar apparatus which concerns on Embodiment 2 of this invention. It is a whole structure of the laser radar apparatus which concerns on Embodiment 3 of this invention. It is an example of a block diagram of the time measurement part which measures the difference of the transmission time of the laser beam in the laser radar apparatus, and the light reception time of reflected light.

Embodiment 1 FIG.
FIG. 1 shows the overall configuration of a laser radar apparatus according to Embodiment 1 of the present invention. The laser radar device according to the first embodiment of the present invention includes an optical transmission / reception unit 10 that oscillates laser light, condenses the reflected light of the laser light, and converts it into a reception signal that is an electrical signal, and a measurable time interval. A distance signal indicating a distance from the sensor to the laser beam irradiation point and an intensity signal indicating the reflected light intensity of the laser beam from the laser irradiation point are calculated from the reception signal converted by the optical transceiver 10 with a variable time standard. A distance intensity calculating unit 20 and a signal processing unit 30 that detects a target from the distance signal and the intensity signal, and calculates an optimal measurable distance interval for the detected target. The distance intensity calculation unit 20 includes an intensity measurement unit 21, a time measurement unit 22, a distance calculation by the trigger generation unit 11, the laser unit 12, the scanner unit 13, the angle monitor unit 14, the reception lens unit 15, and the light receiver unit 16. The section 23, the signal processor 30, the distance strength image calculating unit 31, the target detection unit 32, by the optimum measurement distance interval calculating unit 33 are respectively configured.

  The trigger generation unit 11 generates a trigger signal that serves as a reference for the oscillation time of the laser beam, and outputs the trigger signal to the laser unit 12 and the time measurement unit 22. The laser unit 12 performs laser processing based on the trigger signal generated by the trigger generation unit 11. Oscillates light. The scanner unit 13 two-dimensionally scans the reception visual field, which is an angle range in which the laser beam oscillated by the laser unit 12 and the reflected light of the laser beam can be received, and the angle monitor unit 14 reads the scanner angle of the scanner unit 13 at that time. And output to the distance intensity image calculation unit 31 as a scanner angle signal.

  The receiving lens unit 15 outputs reflected light obtained by collecting scattered light from the target propagating in the coaxial direction with respect to the center of the receiving field to the light receiving unit 16, and the light receiving unit 16 is collected by the receiving lens unit 15. The reflected light is converted into a received signal that is an electrical signal and output to the intensity measuring unit 21 and the time measuring unit 22.

  The intensity measurement unit 21 measures the peak value of the reception signal converted by the light receiver unit 16 and outputs the corresponding voltage to the distance intensity image calculation unit 31 as an intensity signal.

The time measurement unit 22 is configured as shown in FIG. 12, and has a ramp voltage that increases in proportion to the time as a time standard with the time of the trigger signal generated by the trigger generation unit 11 as the time origin. When the reception signal converted by the light receiver 16 is input, the time measurement unit 22 detects the peak of the reception signal and outputs an S / H trigger. The S / H circuit reads the ramp voltage value at the input timing of the S / H trigger and outputs it to the distance calculation unit 23 as a hold voltage value.
The time measurement unit 22 can change the measurable time interval by changing the lamp voltage proportional constant and the gate time. In the initial measurement, the initial lamp voltage proportionality determined in advance so as to increase the measurable distance interval. set constants C ₁ and the first gate time t _g1, next ramp voltage proportional constant calculated by the optimal measurement distance interval calculating unit 33 so that the measurable distance interval than the first time measurement becomes narrower in the second and subsequent measurement C ₂ to set the next gate time _{t g2.}

The distance calculation unit 23 shown in FIG. 1 calculates the reflected light feedback time from the hold voltage value output by the time measuring unit 22 using the lamp voltage proportional constant and the gate time, and calculates the distance signal from the reflected light feedback time and the light velocity. Is output to the distance intensity image calculation unit 31.
Here, the lamp voltage proportional constant and the gate time used for calculating the reflected light feedback time is a value set in the time measuring unit 22, set the initial ramp voltage proportional constant C ₁ and the first gate time t _g1 in the first measurement It is, in the second and subsequent measurements are set to the optimum measurement distance next interval calculated by the calculating unit 33 the lamp voltage proportional constant C ₂ and the next gate time t _g2.

  The distance intensity image calculation unit 31 is obtained from the two-dimensional information of the laser beam irradiation point obtained from the scanner angle signal output from the angle monitor unit 14, the distance signal obtained from the distance calculation unit 23, and the intensity measurement unit 21. The target detection unit 32 calculates three-dimensional distance image data, which is spatially three-dimensional image data, and two-dimensional intensity image data, which is spatially two-dimensional reflected light intensity image data, generated by the intensity signal. Output to.

  The target detection unit 32 detects a target from the three-dimensional distance image data and the two-dimensional intensity image data calculated by the distance intensity image calculation unit 31, and target distance data indicating the distance to the detected target and reflection of the detected target. Target intensity data indicating the light intensity is calculated and output to the optimum measurable distance interval calculator 33.

  The optimum measurable distance interval calculation unit 33 calculates the optimum measurable distance interval from the target distance data output by the target detection unit 32, and calculates the lamp voltage proportional constant signal and the gate signal based on the calculated measurable distance interval. And output to the time measuring unit 22 and the distance calculating unit 23.

Here, calculation of the optimum measurable distance interval and the lamp voltage proportional constant signal and the gate signal based on this will be described. FIG. 2 is a graph showing the lamp voltage at the time of the first measurement of the laser radar device according to the first embodiment of the present invention. The time origin in FIG. 2 is the laser oscillation timing, and the lamp voltage start time (initial gate time). T _g1 , the slope of the lamp voltage is C ₁ , the maximum value of the lamp voltage is V _max , and the lamp voltage end time is t _max1 . If the speed of light is c, the measurable distances L _{min1 to} L _{max1 at} this time are t _g1 × c to t _max1 × c. Two parameters that can be set in the lamp voltage are the lamp voltage start time and the lamp voltage slope, and the maximum value V _max of the lamp voltage is an invariable value. Further, t _max1 is expressed by the formula (1).
t _max1 = t _g1 + V _max / C ₁ (1)

FIG. 3 is a graph showing the initial measurement and resetting of the measurable distance interval of the laser radar device according to the first embodiment of the present invention. Receiving the laser light reflected at a certain time t, and outputs the instantaneous lamp voltage V _R as a hold voltage value. The relationship between the hold voltage value _VR1 and time t is shown in Expression (2).
V _R1 = C ₁ × (t−t _g1 ) (2)
Further, the lamp voltage error at this time is [Delta] V _R1.

The time error Δt ₁ is calculated backward from the lamp voltage error ΔV _R1 . The relationship between Δt ₁ and ΔV _R1 is expressed by Equation (3).
Δt ₁ = ΔV _R1 / C ₁ (3)
Further, the distance error ΔL is expressed by Expression (4) using the speed of light c.
ΔL ₁ = c × Δt ₁ (4)

Here, the lamp voltage start time t _g2 and the end time t _max2 next lamp voltage, to match the time error Δt as shown in FIG. 3, to reset the ramp voltage starting time and the lamp voltage gradient. The measurable distances L _{min2 to} L _{max2 at} this time are t _g2 × c to t _max2 × c. Since this measurable distance is the minimum measurable distance including a distance error, it is an “optimum measurable distance interval”. Further, when the lamp voltage slope of this time and C _2, the lamp voltage start time t _g2 and lamp voltage gradient C ₂ next ramp voltage represented by the formula (5), equation (6).
_{t g2 = t-Δt 1/} 2 (5)
C ₂ = V _max / Δt ₁ (6)
Further, the lamp voltage end time t _max2 is expressed by Expression (7).
_{t max2 = t + Δt 1/} 2 (7)

Next, similarly to the first measurement, the next measurement is performed using the lamp voltage with the measurable distance interval reset. FIG. 4 is a graph showing the lamp voltage at the next measurement of the laser radar device according to the first embodiment of the present invention. The timing for receiving the laser diffused light is t as in FIG. Hold voltage value V _R2 that is held at this time is represented by the formula (8).
V _R2 = C ₂ × (t−t _g2 ) (8)
Further, the lamp voltage error are the same [Delta] V _R as FIG.

Calculated backward the time error Delta] t ₂ from the lamp voltage similar to the initial measurement error [Delta] V _R. Relationship Delta] t ₂ and [Delta] V _R is represented by formula (9).
Δt ₂ = ΔV _R / C ₂ (9)
Further, the distance error ΔL ₂ is expressed by Expression (10).
ΔL ₂ = c × Δt ₂ (10)

The result of comparing the distance error ΔL ₁ at the time of the first measurement and the distance error ΔL ₂ at the time of the next measurement is shown in Expression (11) using (4), Expression (6), Expression (9), and Expression (10). .

ΔL ₂ / ΔL ₁ = Δt ₂ / Δt ₁ = ΔV _R / C ₂ / Δt ₁ = ΔV _R / V _max (11)

From the above, by setting the optimum measurable distance, the distance error can be reduced to ΔV _R / V _max .

  Next, the operation of the laser radar device according to the first embodiment will be described. FIG. 5 is a flowchart of the processing procedure of the laser radar apparatus according to Embodiment 1 of the present invention. First, the time measuring unit 22 sets initial values for the lamp voltage proportional constant and the gate time (step ST1).

  Next, the trigger generation part 11 produces | generates a trigger signal, and the laser part 12 oscillates a laser beam based on this trigger signal (step ST2).

  Next, the receiving lens unit 15 having the center of the receiving field oriented in the direction coaxial with the propagation direction of the laser beam collects the reflected light from the target, and receives the reflected light collected by the receiving lens unit 15. The instrument unit 16 converts the received signal, which is an electrical signal, to output to the intensity measuring unit 21 and the time measuring unit 22 (step ST3). The intensity measuring unit 21 reads the reflected light intensity of the laser light from the received signal converted by the light receiving unit 16, and outputs it as an intensity signal to the distance intensity image calculating unit 31 (step ST4).

  Next, when the reception signal converted by the light receiver unit 16 is input to the time measurement unit 22, the time measurement unit 22 reads the instantaneous lamp voltage value and outputs it as a hold voltage value to the distance calculation unit 23 ( Step ST5), the distance calculation unit 23 calculates the reflected light feedback time from the hold voltage value output by the time measurement unit 22, and calculates the distance from the sensor to the laser beam irradiation point from the reflected light feedback time and the light velocity, It outputs to the distance intensity image calculation part 31 as a distance signal (step ST6).

Here, FIG. 6 is a diagram showing a time change of the lamp voltage of the time measuring unit 22 in the laser radar apparatus according to Embodiment 1 of the present invention. When the trigger signal generated by the trigger generation unit 11 is a time origin, the initial hold voltage value of the time measurement unit 22 is V _R , the initial gate time is t _g1 , and the initial ramp voltage proportional constant is C _1. The process in which the distance calculation unit 23 calculates the reflected light feedback time t from the hold voltage value output by 22 is expressed by Expression (12).

t = V _R / C ₁ + t _g1 (12)

That is, the distance calculation unit 23 by the formula (12), the reflected light feedback time t from the target from the first ramp voltage proportional constant C ₁ and the first gate time t _g1 set in the first hold voltage values V _R and the step ST1 calculate.

  Next, as shown in FIG. 5, the angle monitor unit 14 outputs a scanner angle signal, and the scanner unit 13 is driven to scan the laser (step ST7). Then, the distance intensity image calculation unit 31 determines whether the two-dimensional scanning is completed from the output scanner angle signal (step ST8).

  When the distance intensity image calculation unit 31 determines that the two-dimensional scanning is not completed (NO in step ST8), the process returns to step ST2 and repeats the process. On the other hand, when the distance intensity image calculation unit 31 determines that the two-dimensional scanning has been completed (YES in step ST8), the distance intensity image calculation unit 31 calculates the three-dimensional distance image data and the two-dimensional intensity image. Data is calculated and output to the target detection unit 32 (step ST9).

  It is determined whether the target detection unit 32 has detected a target from the three-dimensional distance image data and the two-dimensional intensity image data output by the distance intensity image calculation unit 31 (step ST10). When the target detection unit 32 determines that the target has not been detected (NO in step ST10), the process returns to step ST1 and the process is repeated. On the other hand, when it is determined that the target detection unit 32 has detected the target (YES in step ST10), target distance data and target intensity data are calculated (step ST11), and the optimum measurable distance interval calculation unit 33 is calculated. Output.

Next, the optimum measurable distance interval calculation unit 33 calculates the optimum measurable distance interval from the target distance data calculated by the target detection unit 32, and the next lamp voltage proportional constant C ₂ is adjusted to the optimum measurable distance interval. The next gate time _tg2 is calculated (step ST12).

Thereafter, the optimum measurement distance interval calculating unit 33, and outputs the calculated next ramp voltage proportional constant C ₂ next gate time t _g2 each ramp voltage proportional constant signal and time measuring unit 22 and the distance calculation unit 23 as a gate signal Then, resetting is performed (step ST13), and the process returns to step ST2 to repeat the process.

Resetting the time measuring unit 22 and the distance calculation unit 23, the next time the lamp voltage proportional constant C ₂ and the next gate time calculated by the optimum measurement distance interval calculating unit 33 the time measuring unit 22 for lamp voltage proportional constant and the gate time Set _tg2 respectively. Therefore, the reflected light feedback time t calculated by the distance calculation unit 23 in step ST6 in the next measurement is expressed by Expression (13). In addition, FIG. 6 shows the time change of the lamp voltage in the next measurement.

t = V _R / C ₂ + t _g2 (13)

  As described above, the measurement accuracy can be improved by repeating the resetting of the gate time and the lamp voltage proportional constant a plurality of times based on the measurement result.

  Here, the calculation of the optimum measurable distance interval by the optimum measurable distance interval calculating unit 33 may be performed using not only the target distance data but also the target intensity data. As described above with reference to FIG. 3, the optimum measurable distance is determined by the target distance data and the lamp voltage error, and in the normal case, a preset value is used for the lamp voltage error. However, the larger the target intensity data is, the smaller the lamp voltage error is. Therefore, it is possible to optimize and reset the error using this correspondence. As a result, the optimum measurable distance can be measured in accordance with the fluctuating error.

  When calculating the optimum measurable distance interval using the target intensity data, the higher the target intensity value indicated by the target intensity data, the higher the distance measurement accuracy. Therefore, when the target intensity value is high in the first measurement, the distance measurement accuracy is also high, so that a more accurate distance measurement can be performed in the next measurement.

FIG. 7 is a diagram showing the time change of the lamp voltage when the signal intensity indicated by the target intensity data of the laser radar apparatus according to Embodiment 1 of the present invention is high and when the signal intensity is low. As shown in FIG. 7, sets the next gate time t _g2 than when the intensity of the signal at the first measurement is high strength of the signal is low in the vicinity of the reflected light feedback time, more the next time the lamp voltage proportional constant C ₂ It shall be set large. Thereby, the distance measurement accuracy of the next measurement can be increased according to the intensity value at the first measurement.

The next gate time _tg2 may be set as close as possible to the reflected light feedback time. For example, in FIG. 3, if inversely proportional to the lamp voltage error [Delta] V _R and the intensity signal I, [Delta] V _R is expressed by Equation (14) using a constant k.
ΔV _R = k / I (14)
Then, the gate time t _g2 is set as shown in Expression (15) from Expression (3), Expression (5), and Expression (14).
t _g2 = t−k / 2C ₁ I (15)
Therefore, it can be said that the stronger the intensity signal I, the closer the gate time _tg2 can be set to the reflected light feedback time t.

Further, as shown in FIG. 7, the lamp voltage, which is the time standard of the time measuring unit 22, increases in proportion to the time by integrating the constant current over time. Here, if the constant current source having a constant current noise I _n, noise V _n of the hold voltage value indicating the lamp voltage can be calculated by equation (16) using a ramp voltage proportional constant C.

Here, in FIG. 3, since the lamp voltage error [Delta] V _R is proportional to the time elapsed from the gate time t _g2, [Delta] V _R is expressed by equation (17) using the proportionality constant h.
ΔV _R = h (t−t _g2 ) (17)
Therefore, by setting the gate time _tg2 so that the elapsed time from the gate time _tg2 to the reflected light feedback time t is as short as possible, an increase in noise can be suppressed, and highly accurate distance measurement can be performed.

  Further, the center of the reception visual field and the laser light propagation direction do not have to be coaxial. FIG. 8 is a diagram showing a configuration when the center of the reception field of view and the laser beam propagation direction are not coaxial in the overall configuration of the laser radar device of FIG. When the center of the reception field and the laser beam propagation direction are not coaxial, the scanner unit 13 does not scan the reception field as shown in FIG. 8, but only the laser beam is two-dimensionally scanned in the fixed field of the reception lens unit 15.

  By separating the reception field of view from the scanner unit 13, the reception aperture is not limited by the size of the scanner unit 13, and the received light intensity can be increased.

  The scanning performed by the scanner unit 13 may be two-dimensional scanning or one-dimensional scanning. In the case of one-dimensional scanning, it becomes a line sensor and acquires one-dimensional distance data and intensity data.

  The scanner unit 13 may not be provided. In the case where the scanner unit 13 is not provided, the laser radar device according to the first embodiment is a fixed-point distance measuring device and can acquire distance data and intensity data at a fixed point. In this case, in addition to the scanner unit 13, the angle monitor unit 14, the distance intensity image calculation unit 31, and the target detection unit 32 are not necessary. The optimum measurable distance interval calculation unit 33 calculates an optimum measurable distance interval from the distance signal and the intensity signal.

  As described above, the optical transmission / reception unit 10 that oscillates the laser beam toward the target, receives the reflected light from the target and converts it into a reception signal, and the optical transmission / reception unit based on a preset measurable time interval. A distance signal indicating the distance to the target by measuring the time from the oscillation of the laser beam by 10 to the reception of the reflected light, and a distance intensity calculator 20 for calculating an intensity signal indicating the intensity of the received signal; A signal processing unit 30 for setting a measurable time interval narrower than a measurable time interval set in advance based on the distance signal and the intensity signal calculated by the distance intensity calculating unit 20, and the distance intensity calculating unit 20 is a signal processing unit. Since the distance signal is calculated based on the narrow measurable time interval set by 30, it is high without providing any other distance measuring device other than the laser radar device. Away measurement accuracy and wide measurable distance interval can be combines.

Embodiment 2. FIG.
FIG. 9 shows the overall configuration of the laser radar apparatus according to the second embodiment of the present invention. Compared with the configuration of the laser radar apparatus shown in FIG. In addition to the 30 configurations. The same reference numerals as those in FIG. 1 denote the same or relative parts, and thus description thereof is omitted.

  The target distance error calculation unit 34 calculates a target distance error value from a preset target maximum moving speed and the time required for one measurement, and outputs the target distance error value to the optimum measurable distance interval calculation unit 33 as target distance error data.

The optimum measurable distance interval calculation unit 33 not only calculates the optimum measurable distance interval from the target distance data and target intensity data calculated by the target detection unit 32 but also the target distance error value calculated by the target distance error calculation unit 34. It is used to output optimum measurement distance to calculate the interval between the next ramp voltage proportional constant C ₂ for the next gate time t _g2 lamp voltage proportional constant signal respectively, the time measuring unit 22 as a gate signal.

When the target maximum moving speed v _t can be assumed, the target distance error calculating unit 34 determines the maximum distance that the target moves from the target maximum moving speed v _t and the time difference Δt _d between the first measurement and the next measurement in the distance intensity image acquisition. The target distance error ΔL shown in FIG. An expression representing the target distance error ΔL is shown in Expression (18).

The target distance error calculation unit 34 calculates the target distance error ΔL from the preset target maximum moving speed v _t and the time difference Δt _d using the equation (18) and outputs the target distance error ΔL to the optimum measurable distance interval calculation unit 33. .

The optimum measurable distance interval calculation unit 33 calculates the target reflected light feedback time error Δt _r ′ from the target distance error ΔL calculated by the target distance error calculation unit 34. Expression (19) is an expression representing the target reflected light feedback time error Δt _r ′ from the target distance error ΔL. Here, c indicates the speed of light.

Optimal measurement distance interval calculating unit 33 using equation (19), the target distance error ΔL goal of the reflected light back time to _'is calculated, the calculated Delta] t _r' error Delta] t r a next gate time with t _g2 next to set the lamp voltage proportional constant C _2.

FIG. 10 is a diagram showing a change over time in the lamp voltage of the laser radar apparatus according to Embodiment 2 of the present invention. The next gate time t _g2 and the next lamp voltage proportional constant C ₂ are set so as to include the width of the reflected light feedback time error Δt _r ′ as shown in FIG.

For example, in FIG. 3, assuming that the target moves, the target moving distance error ΔL _m is added to the distance error ΔL ₁ . Therefore, the distance error ΔL ₁ ′ is expressed by Expression (20).
ΔL ₁ ′ = ΔL ₁ + ΔL _m (20)
Δt ₁ ′ is calculated from the time error ΔL ₁ ′ calculated from the equation (20), and the next gate time t _g2 and the next lamp voltage proportional constant C ₂ are set according to the equations (5) and (6).

  As described above, the signal processing unit 30 includes the target distance error calculation unit 34 that calculates the target distance error value from the preset maximum moving speed of the target and the time required for one measurement. Since the measurable time interval that is narrower than the measurable time interval is calculated using, the target is within the measurable distance interval even if the target moves, so that the target can be detected.

Embodiment 3 FIG.
FIG. 11 shows the overall configuration of the laser radar device according to the third embodiment of the present invention, which additionally includes a trigger cycle control unit 41 in addition to the configuration of the laser radar device shown in FIG. 1 of the first embodiment. It is. The same reference numerals as those in FIG. 1 denote the same or relative parts, and thus description thereof is omitted.

  The trigger cycle control unit 41 calculates an optimum trigger cycle signal from the gate signal and the lamp voltage proportional constant signal calculated based on the measurable distance interval calculated by the optimum measurable distance interval calculation unit 33, and generates a trigger generation unit. 11 is output.

The optimum trigger cycle signal calculation method will be described. The trigger cycle T ₁ takes a value larger than the lamp voltage end time t _max1 that is the measurement end time.
T ₁ > t _max1
For example, it is assumed that the reset lamp voltage end time t _max2 is 1 / A times the initial lamp voltage time t _max1 (A is a constant).
t _max2 = t _max1 / A
Then, it is possible to 1 / A times in accordance with a change of the trigger period T ₂ which is reset also the lamp voltage end time.
T ₂ = T ₁ / A
Thus, data acquisition can be speeded up by shortening the trigger cycle.

  When an optimal trigger cycle signal is output by the trigger cycle control unit 41, the trigger generation unit 11 generates a trigger at a cycle corresponding to the optimal trigger cycle signal.

  In order to measure the reflected light feedback time, the laser unit 12 needs to wait for oscillation of the next laser beam for a measurable time interval corresponding to the measurable distance interval. When the measurable distance interval is wide, the measurable time interval becomes long, so it is necessary to lengthen the oscillation repetition period of the laser beam. Conversely, when the measurable distance interval is narrow, the measurable time interval is shortened, and the laser light oscillation period can be shortened.

  In the laser radar device according to the third embodiment, the measurable distance interval is optimized in the vicinity of the target distance in the second and subsequent measurements, so the measurable time interval becomes small. Therefore, in the laser radar device according to Embodiment 3 of the present invention, the trigger cycle control unit 41 calculates the measurable time interval from the ramp voltage proportional constant signal calculated by the optimum measurable distance interval calculating unit 33 and the gate signal. Then, the trigger period for determining the optimum trigger period of the laser beam is calculated according to the calculated measurable time interval.

  As described above, the trigger cycle control unit 41 that calculates the optimum trigger cycle signal from the measurable time interval narrower than the measurable time interval is provided, and the optical transceiver 10 triggers at a cycle according to the optimum trigger cycle signal. Therefore, in the second and subsequent measurements, the laser beam can be oscillated at a cycle corresponding to the optimum trigger cycle signal, and the laser oscillation repetition cycle can be shortened.

  In addition, since the imaging interval of one distance intensity image is proportional to the laser oscillation cycle, the imaging cycle of the distance intensity image can be shortened in the second and subsequent measurements by shortening the laser oscillation repetition cycle.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 10 Optical transmission / reception part, 11 Trigger generation part, 12 Laser part, 13 Scanner part, 14 Angle monitor part, 15 Reception lens part, 16 Light receiver part, 20 Distance intensity | strength calculation part, 21 Intensity measurement part, 22 Time measurement part, 23 Distance calculation unit, 30 signal processing unit, 31 distance intensity image calculation unit, 32 target detection unit, 33 optimum measurable distance interval calculation unit, 34 target distance error calculation unit, 41 trigger cycle control unit.

Claims (4)

An optical transceiver that oscillates laser light toward a target, receives reflected light from the target, and converts it into a received signal;
Based on a preset measurable time interval, it calculates a distance signal indicating the distance to the laser beam irradiation point by measuring the time from the oscillation of the laser beam by the optical transceiver to reception of the reflected light. A distance intensity calculation unit for calculating an intensity signal indicating the intensity of reflected light of the laser beam from the irradiation point of the laser beam;
A signal processing unit for setting a measurable time interval narrower than the preset measurable time interval based on the distance signal and the intensity signal calculated by the distance intensity calculating unit,
The laser radar apparatus according to claim 1, wherein the distance intensity calculation unit calculates a distance signal based on a narrow measurable time interval set by the signal processing unit. The transmission / reception unit includes a scanner unit that two-dimensionally scans the reception field of the oscillated laser beam and the reflected light of the laser beam, and an angle monitor unit that reads a scanner angle of the scanner unit and outputs the scanner angle to the signal processing unit. Have
The laser radar device according to claim 1, wherein the signal processing unit calculates a measurable time interval narrower than the measurable time interval based on a scanner angle read by the angle monitor unit. The signal processing unit includes a target distance error calculation unit that calculates a target distance error value from a preset target maximum moving speed and a time required for one measurement, and a measurable time using the target distance error value The laser radar device according to claim 1, wherein a measurable time interval narrower than the interval is calculated. A trigger cycle controller that calculates an optimal trigger cycle signal from a measurable time interval narrower than the measurable time interval;
The laser radar device according to claim 1, wherein the transmission / reception unit generates a trigger at a cycle according to the optimum trigger cycle signal.

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