WO2022259344A1

WO2022259344A1 - Laser radar device

Info

Publication number: WO2022259344A1
Application number: PCT/JP2021/021652
Authority: WO
Inventors: 祐一西野; 貴敬中野
Original assignee: 三菱電機株式会社
Priority date: 2021-06-08
Filing date: 2021-06-08
Publication date: 2022-12-15
Also published as: JPWO2022259344A1; JP7345706B2

Abstract

This laser radar device (100) comprises: a scanner (5) that performs one dimensional scanning by using laser light such that the scanning direction on a road becomes oblique with respect to the advancing direction of a vehicle; a position change calculation unit (20) that detects the head of the vehicle and calculates a position change of the head of the vehicle in the advancing direction, on the basis of a reception signal acquired through the one dimensional scanning by the scanner (5); and a vehicle speed calculation unit (12) that measures the speed of the vehicle on the basis of the position change calculated by the position change calculation unit (20).

Description

Laser radar device

The present disclosure relates to a laser radar device.

Conventionally, a two-dimensional scanning laser radar device is used to measure the speed of vehicles traveling on roads. A two-dimensional scanning laser radar device measures the movement amount and movement time of a vehicle, and calculates the speed of the vehicle based on the measured movement amount and movement time.

In Patent Document 1, the vehicle speed is sequentially measured in real time while tracking the vehicle by a two-dimensional scanning laser radar device, and the vehicle length is measured by integrating the sequentially obtained vehicle speed with the time difference between the vehicle speed measurement times. A velocity measuring device is disclosed.

JP-A-11-23250

As described above, in the conventional technology, it is necessary to use a two-dimensional scanning laser radar device in order to measure the movement amount and movement time of the vehicle and to calculate the speed of the vehicle. However, in general, the two-dimensional scanning laser radar device has a problem that the cost is higher than that of the one-dimensional scanning laser radar device. Therefore, a method of measuring the speed of a vehicle using a one-dimensional scanning laser radar device is conceivable, but in that case, there is a problem that at least two one-dimensional scanning laser radar devices are required.
The present disclosure has been made to solve the problems described above, and provides a technology capable of measuring the speed of a vehicle using a single one-dimensional scanning laser radar device.

A laser radar device according to the present disclosure is a laser radar device that measures the speed of a vehicle traveling on a road, and uses laser light so that the scanning direction on the road is oblique to the traveling direction of the vehicle. and the head of the vehicle is detected based on the received signal obtained by the one-dimensional scanning of the scanner, and the change in the position of the head of the vehicle in the direction of travel is calculated, or the tail of the vehicle is detected. and a position change calculation unit that calculates a position change of the tail of the vehicle in the traveling direction, and a vehicle speed calculation unit that measures the speed of the vehicle based on the position change calculated by the position change calculation unit. there is

According to the present disclosure, the speed of a vehicle can be measured with a single one-dimensional scanning laser radar device.

1 is a block diagram showing the configuration of a laser radar device according to Embodiment 1; FIG. 4 is a flowchart showing a vehicle speed measurement method using the laser radar device according to Embodiment 1; It is a figure which shows the one-dimensional scanning by the conventional laser radar apparatus. 4 is a diagram showing one-dimensional scanning by the laser radar device according to Embodiment 1; FIG. 4 is a diagram showing coordinate conversion on a road by the laser radar device according to Embodiment 1; FIG. FIG. 4 is a diagram showing a scanning width in the transverse direction of a road by the laser radar device according to Embodiment 1; 2 is a block diagram showing the configuration of a laser radar device according to Embodiment 2; FIG. 7 is a flowchart showing a vehicle speed measurement method using a laser radar device according to Embodiment 2; 9A is a block diagram showing a hardware configuration that implements the functions of the laser radar device according to Embodiment 1 or the laser radar device according to Embodiment 2. FIG. 9B is a block diagram showing a hardware configuration for executing software that realizes the functions of the laser radar device according to Embodiment 1 or the laser radar device according to Embodiment 2. FIG.

Hereinafter, in order to describe the present disclosure in more detail, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings.
Embodiment 1.
FIG. 1 is a block diagram showing the configuration of a laser radar device 100 according to Embodiment 1. As shown in FIG. As shown in FIG. 1, the laser radar device 100 includes a signal generator 1, a laser light source 2, a transmission optical section 3, a mirror 4, a scanner 5, a reception optical section 6, a photodetector 7, a position change calculation section 20, a vehicle speed A calculation unit 12, a vehicle length calculation unit 13, and a data storage unit 14 are provided. The position change calculator 20 includes a distance calculator 8 , a three-dimensional coordinate converter 9 , a road coordinate converter 10 , and a head/tail detector 11 . Although not shown, the laser radar device 100 is fixed by the sensor fixing portion 15 to a gatepost straddling the road on which the vehicle travels or a pillar installed on the side of the road on which the vehicle travels.

The signal generator 1 is a device that generates a reference trigger signal for synchronizing the laser light source 2 and the scanner 5 at regular intervals. More specifically, the signal generator 1 outputs a laser modulation signal to the laser light source 2 as a reference trigger signal, and synchronously outputs a scanner drive signal to the scanner 5 as a reference trigger signal. The signal generator 1 also outputs a reference signal to the distance calculator 8, which serves as a reference when measuring the distance. In Embodiment 1, the reference signal is a pulse signal or an intensity modulated signal.

The laser light source 2 outputs laser light to the transmission optical section 3 . More specifically, the laser light source 2 modulates the laser light by modulating the current, which is the source of the laser light, based on the modulation signal output from the signal generator 1, and modulates the laser light. is output to the transmission optical unit 3 . In this case, a configuration may be employed in which an external modulator such as an LN (LiNbO3) intensity modulator is used to modulate the laser light. For example, an LD (Laser Diode) or the like is used as the laser light source 2 .

The transmission optical unit 3 shapes the laser light output from the laser light source 2 into a desired beam diameter and divergence angle, and emits the shaped laser light to the mirror 4 . For example, a collimator lens, a condenser lens, or the like is used as the transmission optical unit 3 .
The mirror 4 irradiates the scanner 5 with the laser light that has passed through the transmission optical unit 3 by reflecting the laser light.

The scanner 5 uses laser light to perform one-dimensional scanning so that the scanning direction on the road is oblique to the traveling direction of the vehicle. That is, the scanner 5 uses laser light to perform one-dimensional scanning so that the angle formed by the scanning direction on the road and the traveling direction of the vehicle is an angle other than 0 degree and 90 degrees.

More specifically, in Embodiment 1, the scanner 5 is driven based on the scanner drive signal generated by the signal generator 1, and directs the laser light reflected by the mirror 4 toward the road or a vehicle running on the road. to irradiate. The scanner 5 also reflects the laser beam reflected by the road or the vehicle traveling on the road toward the receiving optical unit 6 .

The scanner 5 outputs angle information regarding the scanning angle when one-dimensional scanning is performed to the three-dimensional coordinate conversion section 9 of the position change calculation section 20 . For example, as the scanner 5, a polygon scanner, a galvanomirror, a MEMS (Micro Electro Mechanical Systems) scanner, or the like is used.

The receiving optical unit 6 collects the laser light reflected by the road or a vehicle traveling on the road and reflected by the scanner 5 and outputs it to the photodetector 7 . For example, a collimating lens, a condensing lens, or the like is used as the receiving optical unit 6 .

The photodetector 7 acquires a received signal by converting the laser light output by the receiving optical section 6 into an electrical signal. The photodetector 7 outputs the acquired received signal to the position change calculator 20 . In Embodiment 1, the received signal is a pulse signal or an intensity modulated signal. For example, as the photodetector 7, a PD (Photo Diode), APD (Avalanche Photo Diode), or the like is used. For example, when converting the output current of a PD or APD into a voltage, a TIA (Trans Impedance Amplifier) is used.

The position change calculator 20 detects the head of the vehicle based on the received signal obtained by the one-dimensional scanning of the scanner 5, and calculates the position change of the head of the vehicle in the traveling direction of the vehicle. The tail is detected and the change in position of the tail of the vehicle in the direction of travel of the vehicle is calculated. More specifically, in Embodiment 1, the position change calculator 20 detects the head and tail of the vehicle based on the received signal obtained by the one-dimensional scanning of the scanner 5 . The position change calculator 20 outputs the calculated position changes to the vehicle speed calculator 12 and the vehicle length calculator 13, respectively.

More specifically, in Embodiment 1, the distance calculator 8 of the position change calculator 20 calculates the distance to the vehicle based on the received signal obtained by the one-dimensional scanning of the scanner 5 . The distance is the distance from the laser radar device 100 to the vehicle. The distance calculator 8 outputs the calculated distance to the three-dimensional coordinate conversion section 9 .

More specifically, in the first embodiment, the distance calculator 8 calculates the distance to the vehicle from the time difference or phase difference between the received signal output by the photodetector 7 and the reference signal output by the signal generator 1. do. More specifically, in the first embodiment, distance calculator 8 calculates the distance to the vehicle from the time difference between the pulse signal output by photodetector 7 and the pulse signal generated by signal generator 1 . Alternatively, the distance calculator 8 calculates the distance to the vehicle from the phase difference between the intensity-modulated signal output by the photodetector 7 and the intensity-modulated signal generated by the signal generator 1 .

For example, the distance calculator 8 is composed of a semiconductor integrated circuit implementing a CPU (Central Processing Unit), a one-chip microcomputer, an FPGA (Field-Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit).

The three-dimensional coordinate conversion unit 9 converts the scanning angle of one-dimensional scanning by the scanner 5 and the distance calculated by the distance calculator 8 into three-dimensional coordinates, thereby generating point cloud data of three-dimensional coordinates. In the three-dimensional coordinates, the position of the laser radar device 100 is the origin, the first coordinate axis and the second coordinate axis are coordinate axes along the road, and the third coordinate axis is the coordinate axis along the vertical direction. be. The point cloud data indicates a plurality of points each representing a three-dimensional coordinate position. The three-dimensional coordinate transformation unit 9 outputs the generated point cloud data of three-dimensional coordinates to the on-road coordinate transformation unit 10 .

More specifically, in the first embodiment, the three-dimensional coordinate conversion unit 9 converts the scanning angle indicated by the angle information output by the scanner 5 and the distance output by the distance calculator 8 into three-dimensional coordinates. Generate point cloud data of 3D coordinates. For example, the three-dimensional coordinate transformation unit 9 is configured by a semiconductor integrated circuit mounting a CPU, a one-chip microcomputer, an FPGA, an ASIC, or the like.

The on-road coordinate conversion unit 10 converts the point cloud data of the three-dimensional coordinates generated by the three-dimensional coordinate conversion unit 9 into coordinates with the traveling direction of the vehicle as a first coordinate axis and the crossing direction of the road as a second coordinate axis. Convert to point cloud data. In other words, the road coordinate conversion unit 10 converts the coordinates on the road. More specifically, in the first embodiment, the on-road coordinate transformation unit 10 converts the first coordinate axis of the three-dimensional coordinates generated by the three-dimensional coordinate transformation unit 9 into a coordinate axis along the traveling direction of the vehicle and converts the three-dimensional The three-dimensional coordinates generated by the three-dimensional coordinate transformation unit 9 are converted to the third coordinates along the vertical direction so that the second coordinate axis of the three-dimensional coordinates generated by the coordinate transformation unit 9 becomes the coordinate axis along the transverse direction of the road. is rotated with the coordinate axes of . The road coordinate transformation unit 10 outputs the transformed point cloud data to the head/tail detection unit 11 . For example, the road coordinate conversion unit 10 is configured by a semiconductor integrated circuit mounting a CPU, a one-chip microcomputer, an FPGA, or an ASIC.

The head/tail detection unit 11 detects the head of the vehicle based on the point cloud data converted by the on-road coordinate conversion unit 10, and calculates the position change of the head of the vehicle in the traveling direction of the vehicle. is detected, and the change in position of the tail of the vehicle in the traveling direction of the vehicle is calculated. The head/tail detector 11 outputs the calculated position change to the vehicle speed calculator 12 .

More specifically, in Embodiment 1, the head/tail detector 11 detects the position of the head of the vehicle at the first time and the second position based on the point cloud data converted by the road coordinate converter 10 . and the position of the head of the vehicle at the time of . Further, the head/tail detection unit 11 detects the position of the head of the vehicle in the traveling direction of the vehicle based on the detected position of the head of the vehicle at the first time and the position of the head of the vehicle at the second time. Calculate change. The head/tail detector 11 outputs the time difference between the first time and the second time to the vehicle speed calculator 12 and the vehicle length calculator 13, respectively.

More specifically, in Embodiment 1, the vehicle head/tail detection unit 11 detects the height on the road as a reference based on the point cloud data converted by the road coordinate conversion unit 10. When the object described above is detected for an arbitrary number of frames, it is determined that the vehicle has entered, and the foremost part of the object is determined to be the head of the vehicle. On the other hand, the head/tail detection unit 11 detects an arbitrary number of objects whose height relative to the road is less than a predetermined height threshold based on the point cloud data converted by the road coordinate conversion unit 10. When the object is detected for the frame, it is determined that the vehicle has finished passing, and the rear end of the object is determined to be the tail. The head/tail detection unit 11 is composed of a semiconductor integrated circuit mounting a CPU, a one-chip microcomputer, an FPGA, an ASIC, or the like.

The vehicle speed calculator 12 measures the speed of the vehicle based on the position change calculated by the position change calculator 20 . More specifically, in the first embodiment, the vehicle speed calculation unit 12 adjusts the speed of the vehicle based on the position change calculated by the head/tail detection unit 11 and the time difference between the first time and the second time. Measure speed. For example, the vehicle speed calculation unit 12 is composed of a semiconductor integrated circuit mounting a CPU, a one-chip microcomputer, an FPGA, an ASIC, or the like.

The vehicle length calculation unit 13 detects the head of the vehicle by the position change calculation unit 20, the time when the position change calculation unit 20 detects the tail of the vehicle, and the vehicle speed calculated by the vehicle speed calculation unit 12. to calculate the length of the vehicle. More specifically, in the first embodiment, the vehicle length calculator 13 calculates the time when the head/tail detector 11 detects the head of the vehicle and the time when the head/tail detector 11 detects the tail of the vehicle. The length of the vehicle is calculated based on the time and the vehicle speed calculated by the vehicle speed calculator 12 . That is, the vehicle length calculation unit 13 calculates the vehicle length from the difference between the vehicle speed calculated by the vehicle speed calculation unit 12 and the head passage time and the tail passage time. The vehicle length calculator 13 outputs the calculated vehicle length to the data storage unit 14 . For example, the vehicle length calculation unit 13 is composed of a semiconductor integrated circuit mounting a CPU, a one-chip microcomputer, an FPGA, an ASIC, or the like.

The data storage unit 14 stores the speed calculated by the vehicle speed calculation unit 12 for each vehicle traveling on the road. More specifically, in the first embodiment, the data storage unit 14 stores the speed data calculated by the vehicle speed calculation unit 12 and the speed data calculated by the vehicle length calculation unit 13 in the order in which the vehicle passes under the laser radar device 100 . Save the data of the car length. For example, the data storage unit 14 is composed of a semiconductor integrated circuit mounting a CPU, a one-chip microcomputer, an FPGA, an ASIC, or the like.

The operation of the laser radar device 100 according to Embodiment 1 will be described below with reference to the drawings. FIG. 2 is a flow chart showing a vehicle speed measurement method using the laser radar device 100 according to the first embodiment.

First, the process until the laser radar device 100 calculates the distance to the vehicle will be described. As described above, the laser radar device 100 is fixed by the sensor fixing portion 15 to the gatepost that straddles the road on which the vehicle travels and the pillar installed on the side of the road on which the vehicle travels. More specifically, the laser radar device 100 is installed at the part of the gatepost or the part of the post that can perform one-dimensional scanning in which the scanning direction on the road is oblique to the traveling direction of the vehicle by the scanner 5. ing.

The laser light source 2 generates modulated laser light based on the modulated signal output from the signal generator 1 and outputs the generated laser light to the transmission optical section 3 .
The transmission optical unit 3 shapes the laser light output from the laser light source 2 into a desired beam diameter and divergence angle, and emits the shaped laser light to the mirror 4 .
The mirror 4 irradiates the scanner 5 with the laser light that has passed through the transmission optical unit 3 by reflecting the laser light.

The scanner 5 is driven based on the scanner drive signal generated by the signal generator 1, and outputs the angle information described above to the three-dimensional coordinate conversion section 9. At that time, the scanner 5 uses a laser beam to perform one-dimensional scanning so that the scanning direction on the road is oblique to the traveling direction of the vehicle.

FIG. 3 is a diagram showing one-dimensional scanning by a conventional laser radar device. FIG. 4 is a diagram showing one-dimensional scanning by the laser radar device 100 according to the first embodiment. 3 and 4 are diagrams each showing one-dimensional scanning as seen from a running vehicle, and a plurality of dotted lines in FIGS. 3 and 4 each represent one scanning. In FIG. 4, the upper diagram is a diagram showing the one-dimensional scanning of the vehicle's head at the first time, and the lower diagram is the one-dimensional scanning of the vehicle's head at the second time. It is a figure which shows. As shown in FIG. 3, the conventional laser radar device uses a laser beam to perform one-dimensional scanning on the road so that the scanning direction is perpendicular to the traveling direction of the vehicle. On the other hand, as shown in FIG. 4, the laser radar device 100 according to Embodiment 1 performs one-dimensional scanning with the scanner 5 so that the scanning direction on the road is oblique to the traveling direction of the vehicle.

The scanner 5 reflects the laser beam reflected by the road or the vehicle traveling on the road toward the receiving optics 6 .
The receiving optical unit 6 collects the laser light reflected by the road or a vehicle traveling on the road and reflected by the scanner 5 and outputs the light to the photodetector 7 .
The photodetector 7 acquires a received signal by converting the laser light output by the receiving optical section 6 into an electrical signal.

The distance calculator 8 calculates the distance to the vehicle from the time difference between the received signal output by the photodetector 7 and the reference signal output by the signal generator 1 . The distance calculator 8 outputs the calculated distance to the three-dimensional coordinate conversion section 9 .

When the signal generator 1 generates a pulse signal, the speed of light is c [m/s] and the time difference is Δt _d [s], the distance z [m] is expressed by the following equation (1) .
z=(c×Δt _d )/2 (1)
The signal generator 1 may generate an intensity-modulated signal, and the distance calculator 8 may calculate the distance from the phase difference between the received signal output by the photodetector 7 and the reference signal output by the signal generator 1. .

Each step shown in FIG. 2 will be described below. The three-dimensional coordinate conversion unit 9 converts the scanning angle indicated by the angle information output by the scanner 5 and the distance output by the distance calculator 8 into three-dimensional coordinates, thereby generating point cloud data of three-dimensional coordinates ( step ST1). The three-dimensional coordinate transformation unit 9 outputs the generated point cloud data of three-dimensional coordinates to the on-road coordinate transformation unit 10 .

The on-road coordinate conversion unit 10 converts the point cloud data of the three-dimensional coordinates generated by the three-dimensional coordinate conversion unit 9 into coordinates with the traveling direction of the vehicle as a first coordinate axis and the crossing direction of the road as a second coordinate axis. Convert to point cloud data (step ST2). At that time, the on-road coordinate conversion unit 10 transforms the point cloud data of the three-dimensional coordinates generated by the three-dimensional coordinate conversion unit 9 into the traveling direction of the vehicle according to the following formulas (2) and (3) It is converted into point cloud data of coordinates with the coordinate axis and the crossing direction of the road as the second coordinate axis.
x ₁ =L ₀ ×cos θ _s (2)
y ₁ =L ₀ ×sin θ _s (3)
θ _s [rad] in equations (2) and (3) is the angle formed by the scanning direction on the road and the traveling direction of the vehicle. L ₀ in equations (2) and (3) is the distance from the corresponding position on the road of the laser radar device 100 to the position on the road of the point cloud data of the three-dimensional coordinates generated by the three-dimensional coordinate conversion unit 9. Indicates distance. x1 in equation (2) is the x _- coordinate on the road after transformation. y1 in equation (3) is the y _- coordinate on the road after transformation.

FIG. 5 is a diagram showing coordinate transformation on the road by the laser radar device 100 according to the first embodiment. FIG. 6 is a diagram showing the scanning width in the transverse direction of the road by the laser radar device 100 according to the first embodiment. As shown in FIG. 5, in the coordinates converted by the road coordinate conversion unit 10, the sensor installation position where the laser radar device 100 is installed is the origin, the traveling direction of the vehicle is the x coordinate, and the crossing direction of the road is the y coordinate. The direction perpendicular to the road from the sensor installation position is the z-coordinate. In this case, θ _s [rad] in equations (2) and (3) corresponds to the angle formed by the traveling direction (x-axis) of the vehicle and the scanning direction (trajectory of the laser beam) shown in FIG.

The vehicle head/tail detection unit 11 determines whether or not the vehicle head has been detected based on the point cloud data transformed by the road coordinate transformation unit 10 (step ST3). At that time, the vehicle head/tail detection unit 11 detects an object whose height relative to the road is equal to or higher than a predetermined height threshold based on the point cloud data converted by the road coordinate conversion unit 10. When the object is detected for several frames, it is determined that the vehicle has entered, and the foremost part of the object is determined to be the head of the vehicle.

When it is determined that the head/tail detector 11 has detected the head of the vehicle (YES in step ST3), the laser radar device 100 proceeds to the process of step ST4. When it is determined that the head/tail detector 11 has not detected the head of the vehicle (NO in step ST4), the laser radar device 100 returns to the process of step ST1.

The head/tail detector 11 calculates the position change ΔL [m] of the head (step ST4). L ₁ [m] is the position of the point cloud data of the vehicle head acquired by the vehicle head/tail detection unit 11 at the first time t ₁ [s], and the point cloud of the vehicle head acquired at the second time t ₂ [s] Assuming that the position of the data is L ₂ [m], the position change ΔL [m] of the vehicle head can be expressed by the following equation (4).
ΔL=L ₂ -L ₁ (4)

The head/tail detector 11 calculates the time change Δt [s] of the head in accordance with the following equation (5) (step ST5).
Δt=t ₂ −t ₁ (5)

Assume that the frame rate of the laser radar device 100 is F [Hz], the total number of point cloud data acquired in _one scan is N, and the n1th point cloud data out of N captures the head of the car for the first time ( 4), and if the offset time from the start of scanning is t _o1 [s], the first time t ₁ [s] in Equation (5) is expressed by Equation (6) below: be.
t1=( ₁ /F)*(n1 _/ N)+ _t01 (6)

Similarly, assuming that the n _2nd point cloud data out of N captures the head of the car for the second time (see the lower diagram in FIG. 4), and the offset time from the start of scanning is t _o2 [s], The second time t ₂ [s] is represented by Equation (7) below.
t2 ₌ (1/F) x (n2/N) ₊ _t02 (7)

The vehicle speed calculation unit 12 measures the speed of the vehicle based on the position change calculated by the head/tail detection unit 11 and the time difference between the first time and the second time (step ST6 ). The vehicle speed v _c [km/h] is expressed by the following equation (8), where ΔL [m] is the change in the position of the head or tail of the vehicle, and Δt [s] is the time difference between the first time and the second time. is represented by
v _c =(ΔL/Δt)×3.6 (8)

The vehicle head/tail detection unit 11 determines whether or not the vehicle tail is detected based on the point cloud data converted by the road coordinate conversion unit 10 (step ST7). At this time, the vehicle head/tail detection unit 11 detects an object whose height relative to the road is less than a predetermined height threshold based on the point cloud data converted by the road coordinate conversion unit 10. When the object is detected for several frames, it is determined that the vehicle has passed, and the rear end of the object is determined as the tail.

When it is determined that the vehicle head/tail detector 11 has detected the vehicle tail (YES in step ST7), the laser radar device 100 proceeds to the process of step ST8. When it is determined that the vehicle head/tail detection unit 11 did not detect the vehicle tail (NO in step ST8), the laser radar device 100 acquires again the point cloud data transformed by the road coordinate transformation unit 10, and performs step ST7. process again.

The head/tail detector 11 calculates a vehicle passing time _Δtc , which is the time difference between the time when the head of the vehicle is detected and the time when the tail of the vehicle is detected (step ST8). Assuming that the head detection time is t _s [s] and the tail detection time is t _e [s], the passing time Δt _c [s] of the vehicle is expressed by the following equation (9).
Δt _c =t _e −t _s (9)

The vehicle length calculator 13 calculates the vehicle length based on the vehicle speed calculated by the vehicle speed calculator 12 and the vehicle passing time calculated by the head/tail detector 11 (step ST9). The vehicle length L _c [m] is represented by the following equation (10) based on the above-described vehicle speed v _c and the above-described vehicle passing time Δt _c [s].
L _c =v _c ×Δt _c (10)

The data storage unit 14 stores the speed data calculated by the vehicle speed calculation unit 12 and the vehicle length data calculated by the vehicle length calculation unit 13 in the order in which the vehicle passes under the laser radar device 100 (step ST10). .

The laser radar device 100 determines whether or not to end the acquisition of vehicle speed and vehicle length data (step ST11). When continuing data acquisition (NO in step ST11), the laser radar device 100 returns to the process of step ST1, and when ending data acquisition (YES in step ST11), ends the process (ST11).

As described above, according to Embodiment 1, since one-dimensional scanning is performed so that the scanning direction on the road is oblique to the traveling direction of the vehicle, the point cloud data spreads in the traveling direction of the vehicle. . Accordingly, it is possible to measure the position change of the head or tail of the vehicle and the speed of the vehicle by one-dimensional scanning by the single laser radar device 100 . Further, the distance resolution in the traveling direction of the vehicle is determined by the observation point pitch, and by adjusting the installation angle of the laser radar device 100 according to the maximum detectable speed, measurement with even higher distance resolution becomes possible.

As shown in FIG. 3, when the scanning direction on the road is perpendicular to the traveling direction of the vehicle, the distance resolution in the traveling direction depends on the frame rate of the laser radar device and the speed of the vehicle. Assuming that the frame rate of the laser radar device is F [Hz], the resolution Δx ₁ in the traveling direction is expressed by the following equation (11).
Δx ₁ =(v _c /3.6)×(1/F) (11)

On the other hand, as shown in FIG. 4, when the scanning direction on the road is oblique with respect to the traveling direction of the vehicle, the distance resolution in the traveling direction depends on the horizontal angular resolution and inclination angle of the laser radar device 100 . Let h [m] be the installation height of the laser radar device 100 with respect to the road, let Δθ _h [rad] be the horizontal angular resolution of the laser radar device 100, and let the traveling direction of the vehicle and the scanning direction on the road form Assuming that the angle is θ _s [rad], the resolution Δx ₂ in the traveling direction is expressed by the following equation (12).
Δx ₂ =h×tan Δθ _h ×cos θ _s (12)

As described above, the laser radar device 100 according to Embodiment 1 is a laser radar device 100 that measures the speed of a vehicle traveling on a road, and uses laser light to detect that the scanning direction of the vehicle on the road is A scanner 5 that performs one-dimensional scanning obliquely to the direction of travel, and the head of the vehicle is detected based on the received signal obtained by the one-dimensional scanning of the scanner 5, and the position of the head of the vehicle in the direction of travel is detected. A position change calculation unit 20 that calculates a change or detects the tail of the vehicle and calculates a position change of the tail of the vehicle in the direction of travel; and a vehicle speed calculation unit 12 that measures the speed of the vehicle.

According to the above configuration, one-dimensional scanning is performed so that the scanning direction on the road is oblique to the traveling direction of the vehicle, so it is possible to measure the position change of the vehicle head or tail in the traveling direction. , the speed of the vehicle can be measured. That is, the speed of the vehicle can be measured by one one-dimensional scanning laser radar device.

Embodiment 2.
Embodiment 2 describes a configuration for changing the scanning direction on the road.
Embodiment 2 will be described below with reference to the drawings. In addition, the same reference numerals are given to the configurations having the same functions as the configurations described in the first embodiment, and the description thereof will be omitted.
FIG. 7 is a block diagram showing the configuration of laser radar device 101 according to the second embodiment. As shown in FIG. 7, the laser radar device 101 further includes a sensor rotation determination section 16 and a sensor rotation section 17 in addition to the configuration of the laser radar device 100 according to the first embodiment.
The configuration according to the second embodiment differs from the configuration according to the first embodiment in that the angle formed by the traveling direction of the vehicle and the scanning direction on the road can be changed by the sensor rotation determination unit 16 and the sensor rotation unit 17 .

The sensor rotation determination unit 16 determines whether the speed stored in the data storage unit 14 is equal to or higher than a predetermined speed. More specifically, in the first embodiment, the sensor rotation determination unit 16 rotates the laser radar device 101 based on the speed of the vehicle stored in the data storage unit 14 to determine the distance resolution in the traveling direction of the vehicle. Decide whether to improve. When the sensor rotation determining unit 16 determines to rotate the laser radar device 101 , the sensor rotating unit 17 controls the laser radar device 101 to rotate. For example, the sensor rotation determination unit 16 is configured by a semiconductor integrated circuit mounting a CPU, a one-chip microcomputer, an FPGA, an ASIC, or the like.

The sensor rotation unit 17 performs a rotation operation to rotate the laser radar device 101 based on the determination result of the sensor rotation determination unit 16. More specifically, when the sensor rotation determination unit 16 determines that the speed stored in the data storage unit 14 is equal to or higher than a predetermined speed, the sensor rotation unit 17 determines the scanning direction of the scanner 5 on the road and the vehicle speed. The laser radar device 101 is rotated so that the angle formed with the traveling direction of the laser radar device 101 becomes large. The angle formed by the scanning direction on the road by the scanner 5 and the traveling direction of the vehicle is an acute angle both before and after the rotation of the laser radar device 101 . For example, a motor or the like is used as the sensor rotation unit 17 .

The operation of the laser radar device 101 according to Embodiment 2 will be described below with reference to the drawings. FIG. 8 is a flow chart showing a vehicle speed measurement method using the laser radar device 101 according to the second embodiment. The vehicle speed measurement method by the laser radar device 101 according to the second embodiment is the same as the vehicle speed measurement method by the laser radar device 100 according to the first embodiment except steps ST12 and ST13. Therefore, detailed description of each step from step ST1 to step ST11 described in the first embodiment is omitted.

As shown in FIG. 8, as a next step after step ST10, the sensor rotation determination unit 16 determines whether the speed of the vehicle stored in the data storage unit 14 is equal to or higher than a predetermined speed (step ST12).

When the sensor rotation determination unit 16 determines that the speed stored in the data storage unit 14 is equal to or higher than the predetermined speed (YES in step ST12), the sensor rotation determination unit 16 controls the sensor rotation unit 17 to rotate the laser radar device 101. A control signal is output to the sensor rotating section 17 (step ST13). In step ST13, the sensor rotation unit 17 rotates the laser beam so that the angle formed by the scanning direction on the road by the scanner 5 and the traveling direction of the vehicle increases based on the control signal output by the sensor rotation determination unit 16. Rotate the radar device 101 . Note that the user sets a plurality of rotation angles of rotation by the sensor rotation unit 17 in advance.

When the sensor rotation determination unit 16 determines that the speed stored in the data storage unit 14 is less than the predetermined speed (NO in step ST12), the laser radar device 101 proceeds to the process of step ST11.

According to the above configuration, when there is a vehicle traveling at a speed equal to or higher than a predetermined speed, by increasing the angle formed by the scanning direction on the road by the scanner 5 and the traveling direction of the vehicle, the head of the vehicle or the Increase the number of point cloud data for the tail. However, in that case, the scanning width in the transverse direction on the road becomes narrow. Therefore, the sensor rotation determining unit 16 may set the angle formed by the scanning direction on the road by the scanner 5 and the traveling direction of the vehicle according to the following equation (14) according to the width of the road.

When the conventional laser radar device performs one-dimensional scanning so that the scanning direction on the road is perpendicular to the traveling direction of the vehicle, as shown in FIG. The scan width w _r [m] is represented by the following equation (13), where the full width of the scan angle in the transverse direction by the laser radar device is θ _h [rad].
w _r =2h×tan(θ _h /2) (13)

When one-dimensional scanning is performed by the scanner 5 of the laser radar device 101 according to the second embodiment so that the scanning direction on the road is oblique to the traveling direction of the vehicle, as shown in FIG. The scanning width w _rh [m] in the transverse direction on the road by the scanner 5 of the device 101 (the projection width of the scanning range on the road by the scanner 5 of the laser radar device 101 on the cross section of the road) is given by the following equation ( 14).
w _rh =w _r ×sin θ _s (14)

The scanning width w _rv [m] in the traveling direction of the vehicle by the scanner 5 of the laser radar device 101 (the projection width of the scanning range on the road by the scanner 5 of the laser radar device 101 to the longitudinal section of the road) is obtained by the following equation: (15).
w _rv =w _r ×cos θ _s (15)

As described above, according to Embodiment 2, the setting of the angle between the scanning direction on the road by the scanner 5 and the traveling direction of the vehicle can be changed. It is possible to improve the distance resolution in the traveling direction.

In the laser radar device 100 or the laser radar device 101, the distance calculator 8 of the position change calculator 20, the three-dimensional coordinate converter 9, the road coordinate converter 10, the head/tail detector 11, the vehicle speed calculator 12, the vehicle Each function of the length calculation unit 13 and the sensor rotation determination unit 16 is implemented by a processing circuit. That is, the laser radar device 100 or the laser radar device 101 has a processing circuit for executing the processing of each step shown in FIG. 2 or FIG. This processing circuit may be dedicated hardware, or may be a CPU (Central Processing Unit) that executes a program stored in memory.

FIG. 9A is a block diagram showing a hardware configuration that implements the functions of the laser radar device 100 or the laser radar device 101. FIG. FIG. 9B is a block diagram showing a hardware configuration for executing software realizing the functions of the laser radar device 100 or the laser radar device 101. As shown in FIG.

If the processing circuit is the dedicated hardware processing circuit 110 shown in FIG. 9A, the processing circuit 110 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an Application Specific Integrated Integrated Circuit Circuit), FPGA (Field-Programmable Gate Array), or a combination thereof.

In the laser radar device 100 or the laser radar device 101, the distance calculator 8 of the position change calculator 20, the three-dimensional coordinate converter 9, the road coordinate converter 10, the head/tail detector 11, the vehicle speed calculator 12, the vehicle Each function of the length calculation unit 13 and the sensor rotation determination unit 16 may be realized by separate processing circuits, or these functions may be collectively realized by one processing circuit.

If the processing circuit is the processor 111 shown in FIG. Each function of the head/tail detection unit 11, the vehicle speed calculation unit 12, the vehicle length calculation unit 13, and the sensor rotation determination unit 16 is realized by software, firmware, or a combination of software and firmware.
Software or firmware is written as a program and stored in the memory 112 .

The processor 111 reads out and executes a program stored in the memory 112 to perform the distance calculator 8, the three-dimensional coordinate conversion unit 9, and the road surface of the position change calculation unit 20 in the laser radar device 100 or the laser radar device 101. The functions of the coordinate conversion unit 10, the head/tail detection unit 11, the vehicle speed calculation unit 12, the vehicle length calculation unit 13, and the sensor rotation determination unit 16 are realized. That is, the laser radar device 100 or the laser radar device 101 stores a program that results in the processing of each step shown in FIG. 2 or 8 when these functions are executed by the processor 111. A memory 112 is provided for

These programs are the distance calculator 8 of the position change calculator 20, the three-dimensional coordinate converter 9, the on-road coordinate converter 10, the vehicle head/tail detector 11, the vehicle speed A computer is caused to execute each procedure or method of the calculation unit 12 , the vehicle length calculation unit 13 , and the sensor rotation determination unit 16 . The memory 112 stores the computer in the laser radar device 100 or the laser radar device 101, the distance calculator 8 of the position change calculator 20, the three-dimensional coordinate converter 9, the on-road coordinate converter 10, and the vehicle head/tail detector 11. , the vehicle speed calculation unit 12, the vehicle length calculation unit 13, and the sensor rotation determination unit 16.

The processor 111 corresponds to, for example, a CPU (Central Processing Unit), a processing device, an arithmetic device, a processor, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor).

The memory 112 includes, for example, non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically-EPROM), Magnetic discs such as hard disks and flexible discs, flexible discs, optical discs, compact discs, mini discs, DVDs (Digital Versatile Discs) and the like are applicable.

In the laser radar device 100 or the laser radar device 101, the distance calculator 8 of the position change calculator 20, the three-dimensional coordinate converter 9, the road coordinate converter 10, the head/tail detector 11, the vehicle speed calculator 12, the vehicle A part of each function of the length calculation unit 13 and the sensor rotation determination unit 16 may be realized by dedicated hardware, and a part thereof may be realized by software or firmware.

For example, the functions of the distance calculator 8, the three-dimensional coordinate converter 9, the on-road coordinate converter 10, and the head/tail detector 11 of the position change calculator 20 are realized by a processing circuit as dedicated hardware. do. The functions of the vehicle speed calculation unit 12, the vehicle length calculation unit 13, and the sensor rotation determination unit 16 may be realized by the processor 111 reading and executing a program stored in the memory 112. FIG.
As such, the processing circuitry may implement each of the above functions in hardware, software, firmware, or a combination thereof.
It should be noted that it is possible to freely combine each embodiment, modify any component of each embodiment, or omit any component from each embodiment.

Since the laser radar device according to the present disclosure can measure the speed of a vehicle with a single one-dimensional scanning laser radar device, it can be used as a technology for measuring the speed of a vehicle.

1 signal generator, 2 laser light source, 3 transmission optical unit, 4 mirror, 5 scanner, 6 reception optical unit, 7 photodetector, 8 distance calculator, 9 three-dimensional coordinate conversion unit, 10 road coordinate conversion unit, 11 Vehicle head/tail detection unit 12 Vehicle speed calculation unit 13 Vehicle length calculation unit 14 Data storage unit 15 Sensor fixing unit 16 Sensor rotation determination unit 17 Sensor rotation unit 20 Position

change calculation unit

100, 101 Laser radar Device, 110 processing circuit, 111 processor, 112 memory.

Claims

A laser radar device for measuring the speed of a vehicle traveling on a road,
a scanner that performs one-dimensional scanning using a laser beam so that the scanning direction on the road is oblique to the traveling direction of the vehicle;
Based on the received signal obtained by the one-dimensional scanning of the scanner, the head of the vehicle is detected and the change in position of the head of the vehicle in the direction of travel is calculated, or the tail of the vehicle is detected. , a position change calculation unit that calculates a position change of the tail of the vehicle in the traveling direction;
and a vehicle speed calculator for measuring the speed of the vehicle based on the positional change calculated by the positional change calculator.
The position change calculator detects the head and tail of the vehicle based on the received signal obtained by the one-dimensional scanning of the scanner,
Based on the time when the position change calculation unit detects the head of the vehicle, the time when the position change calculation unit detects the tail of the vehicle, and the vehicle speed calculated by the vehicle speed calculation unit, 2. The laser radar device according to claim 1, further comprising a vehicle length calculator for calculating the vehicle length.
The position change calculation unit
a distance calculator that calculates the distance to the vehicle based on the received signal;
a three-dimensional coordinate conversion unit that converts the scanning angle of the one-dimensional scanning by the scanner and the distance calculated by the distance calculator into three-dimensional coordinates to generate point cloud data of three-dimensional coordinates;
The point cloud data of three-dimensional coordinates generated by the three-dimensional coordinate conversion unit is converted into point cloud data of coordinates with the traveling direction of the vehicle as a first coordinate axis and the crossing direction of the road as a second coordinate axis. a road coordinate transformation unit;
Detecting the head of the vehicle based on the point cloud data converted by the on-road coordinate conversion unit, calculating a position change of the head of the vehicle in the direction of travel, or detecting the tail of the vehicle, 2. The laser radar device according to claim 1, further comprising a front and rear detection section for calculating a position change of the rear of the vehicle in the traveling direction.
The head and tail detection unit detects the position of the head of the vehicle at a first time and the position of the head of the vehicle at a second time based on the point cloud data converted by the road coordinate conversion unit. calculating a change in position of the head of the vehicle in the traveling direction based on the detected position of the head of the vehicle at a first time and the detected position of the head of the vehicle at a second time;
The vehicle speed calculation unit measures the speed of the vehicle based on the positional change calculated by the front and rear detection unit and the time difference between the first time and the second time. Item 4. The laser radar device according to item 3.
The laser radar device according to claim 1, further comprising a data storage unit that stores the speed calculated by the vehicle speed calculation unit for each vehicle traveling on the road.
a sensor rotation determination unit that determines whether the speed stored in the data storage unit is equal to or higher than a predetermined speed;
When the sensor rotation determination unit determines that the speed stored in the data storage unit is equal to or higher than a predetermined speed, the angle formed by the scanning direction of the scanner and the traveling direction of the vehicle is increased. 6. The laser radar device according to claim 5, further comprising: , and a sensor rotating section for rotating the laser radar device.