JP3240839B2 - Vehicle width measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle width measuring device.

[0002]

2. Description of the Related Art As a conventional vehicle type discriminating device, there are a vehicle detector for detecting the entry of a vehicle, a vehicle height detector for comparing the vehicle height with a fixed value, and a license plate reading device for recognizing the size and characters of the license plate. And the like are installed on an island, and the type of the vehicle is determined by the determiner based on the information. FIG. 1 shows an installation example of this kind of vehicle type discriminating apparatus. In FIG. 1, a photoelectric vehicle detector 2 and a photoelectric vehicle height detector 3 are provided on an island 1, and an imaging device 5 and a recognition device 6 are provided near a booth 4 of the island 1. I have. Note that the vehicle detector 2 includes a light emitting unit 2a.
And the light receiving unit 2b, and the vehicle height detector 3 is also formed of a light projecting unit 3a and a light receiving unit 3b. In this vehicle type discriminating apparatus, the vehicle 7 that has entered the vehicle
The height of the vehicle is detected by the vehicle height detector 3 at the vehicle detection timing, and the license plate of the vehicle 7 is imaged by the imaging device 5, and the vehicle detector 2 and the vehicle height detector 3 and the information of the imaging device 5 is a recognition device 6
And the vehicle type is determined.

[0003]

In the above-described conventional vehicle type discriminating apparatus, the island is designed to be long in order to secure a place where devices such as a vehicle detector and a vehicle height detector are installed.
Or an existing island needs to be expanded. However, there is a problem that it is difficult to install a long island at a tollgate on an expressway in a city, and it is difficult to extend the island in many places.

The present invention has been made in view of the above problems, and has as its object to provide a high-precision vehicle type discriminating apparatus which can be easily installed without lengthening or expanding an island. And

[0005]

A vehicle height measuring device according to the present invention comprises a light projecting section for projecting a laser beam, and a projecting section for projecting the projected laser beam in a direction perpendicular to a vehicle approach direction on a road surface. A scanning unit that scans, a light receiving unit that receives reflected light reflected from the road surface or the vehicle, a reflection time calculation unit that calculates a reflection time of the laser light, and a laser light that is reflected from the vehicle. A vehicle height calculation unit that calculates the vehicle height of the vehicle from the reflection time and the reflection time of the laser light when reflected from the road surface; and
Receives reflected light for a shorter time than the reflected time when scanning.
Calculate vehicle width based on scan range when illuminated
A vehicle width calculator .

In this vehicle width measuring device, a laser beam is projected from a light projecting section toward a road surface, and the laser beam is scanned in a direction perpendicular to the vehicle approach direction on the road surface. This laser light is reflected on a road surface or a vehicle, and the reflected light is received by a light receiving unit. The reflection time from when the laser light is projected to the time when it is reflected and received is calculated, and the reflection time of the laser light reflected from the vehicle and the reflection time of the laser light reflected from the road surface are used to calculate the reflection time. Is calculated. Also the road
When it is shorter than the reflection time when scanning the surface with laser light
Based on the range of the scan when receiving the reflected light between
Calculate the vehicle width.

[0007]

The present invention will be described in more detail with reference to the following examples. FIG. 2 is a perspective view showing an installation example of the vehicle type discriminating apparatus according to one embodiment of the present invention. In FIG. 2, three laser radars 13a, 13b, and 13c are provided horizontally on the ceiling 12 on the entrance side of the vehicle relative to a tollgate (booth) 11 in a direction perpendicular to the road on which the vehicle enters. Each of the laser radars 13a, 13b, and 13c is configured to scan in the side-by-side direction. These laser radars 13a,
13b and 13c irradiate the laser directly below and measure the vehicle width from the reflection time. Details of the vehicle width measurement will be described later.

A camera 14 and illuminating lights 15a and 15b are installed on a ceiling 12 near the tollgate 11, and these constitute a vehicle license plate reading device.
The camera 14 constantly captures an image of an object coming into the field of view of the camera, and a plurality of vehicles continuously go to the tollgate 11 to image a license plate portion in front of the vehicle coming into the field of view. In this embodiment, the license plate is set at a depression angle of 45 ° to obtain an image of the license plate so as to prevent characters in the license plate from being hidden by the front bumper etc and becoming unrecognizable. Lighting lamp 15a,
A device 15b emits light mainly for photographing a plate at night, and employs a continuous illumination method. In the conventional method, the control unit receives a signal indicating that the vehicle has been detected by the vehicle detector, and thereby outputs a signal for instructing light emission of the strobe. However, in the continuous illumination system of this embodiment, there is no need to notify the timing of light emission, so that a vehicle detector is not required.

In the conventional method using a strobe, there is a problem that the timing at which the strobe light is emitted and the time at which the plate is photographed by the camera must be the same. However, in the continuous illumination / photographing processing method, since the plate reading processing is performed with an image which is always visible, there is no need to consider the above timing. Each laser radar 13a, 13
b and 13c are both light projecting units 21 as shown in FIG.
, A light-receiving unit 22, and a distance / vehicle width measuring unit 23. The light-emitting unit 21 includes a light-transmitting unit 24, a scanning mechanism 25, and a driving circuit 26. Is provided.

The projector 24 of the projector 21 is, for example, a laser diode. The laser beam 31 output from the projector 24 is scanned downward by the scanning mechanism 25 at a constant speed over a predetermined scanning angle θ. Is done. The scanning mechanism 25 is a laser 31 from the projector 24.
, And a rotating mechanism for swinging the reflecting mirror. However, the present invention is not limited thereto.
The rotation mechanism may be directly connected to the camera to perform the swing operation.

The drive circuit 26 outputs a trigger pulse signal P1 for pulse-driving the light projector 24 at regular intervals. The light receiver 27 of the light receiver 22 is, for example, a photodiode, and the reflected light 32 from the object received by the light receiver 27 is converted into an electric signal and supplied to a light receiving circuit 28 for amplification and waveform shaping. And the like.

A trigger pulse signal P1 for pulse-driving the light projector 24 and an amplified signal P output from the light receiving circuit 28
2. The scan angle signal of the scan mechanism 25 is the distance
The vehicle width is given to the vehicle width measurement unit 23, and the vehicle width is measured. distance·
The vehicle width measuring unit 23 calculates a distance R to the object from the light emitting timing of the light emitting unit 21 and the light receiving timing of the light receiving unit 22 for each laser light emitted.
And a control circuit 30 for performing predetermined processing to be described later using the values calculated by the arithmetic circuit 29 and finally calculating the vehicle width.

Next, the principle of measuring the vehicle width (and height) using a laser radar will be described with reference to FIG. 3 above the vehicle
The laser light is scanned right below by the laser radars 13a, 13b, and 13c, and measurement is performed based on the reflection time. The reflection time when the vehicle 18 is present is shorter than when the road surface 17 is illuminated. By detecting in which range this is, the vehicle width can be measured. The vehicle height can be calculated from the difference between the reflection time on the road surface 17 and the reflection time on the vehicle 18.

That is, in FIG. 4, the scan area of each laser radar is equally divided into N areas, and the reflection time is measured for each area. The scan area D is D = Htan θ [m] in the case of the laser radars 13a and 13c at both ends.
Then, the center laser radar 13b has D ≒ 2Htan (θ /
2) It is determined by [m]. Here, θ [rad] is the scan angle, and H [m] is the set height of the laser radar.
The length of the N-divided area is d [m] = D / N.

Now, as shown in FIG. 4, the laser irradiation area-laser beam reflection time characteristic is as shown in FIG.
On the right side of a2, the laser light reflection times are t ₂ and A, respectively.
Assuming that the reflection time of the laser beam between area ₁ and area 2 is t ₁ , the area of Area ₁ to Area 2 where the reflection time is short corresponds to the vehicle width. Therefore, the vehicle width W [m] is calculated as follows: W [m] = (Area2-Area1) x d = (Area2-Area
1) × Htanθ / N Also, t ₂ -t ₁ corresponds to the vehicle height, and is the round trip time between the ceiling of the vehicle and the road surface. Therefore, the vehicle height R
[M] is R [m] = (t ₂ −t ₁ ) × C / 2 = 1.5 × (t ₂ −
t ₁ ) × 10 ⁸ where C: light speed (3.0 × 10 ⁸ [m / s]).

The discriminating operation of the vehicle type discriminating apparatus according to the embodiment will be described with reference to a flowchart shown in FIG. In the discrimination process, first, it is determined whether the plate size is a large plate or a medium plate based on the image of the license plate read by the license plate reading device (ST1). If the plate is a large plate, it is determined that the vehicle is a large vehicle (ST2). If the plate is a middle plate, it is determined whether the read vehicle type code is 0, 9, or 1 to 8 (ST3). Here, when the vehicle type code is 0 or 9, it is determined that the vehicle is a large vehicle (ST2), and when the vehicle type code is 1 to 8, it is determined that the vehicle is a medium-sized vehicle (ST4).

In ST1, if it is not possible to determine whether the plate size is large or medium, it is determined whether the vehicle width measured by the laser radar exceeds 2200 mm (S1).
T5). If the vehicle width exceeds 2200 mm, the vehicle is determined to be a large vehicle (ST6), and if the vehicle width is 2200 mm or less, it is determined to be a medium vehicle (ST7). In this embodiment, a large car and a normal car are distinguished from each other according to the size of the license plate, the vehicle type code, and the vehicle width. However, the determination is not limited to these two types, and the set value may be changed. By providing a large number, three or more vehicle types can be identified.

FIG. 6 is a schematic diagram for explaining a vehicle type discriminating apparatus according to another embodiment of the present invention. The car 31 shown in FIG.
A pole trailer, which includes a towing vehicle 32 and a towed vehicle 33
Is a special vehicle consisting of a pole 34 connecting them, and when the vehicle width is simply measured, the width of the pole 34 is small, so that it is not determined that the vehicle is a vehicle. It may be determined as if it exists.

In this embodiment, utilizing the high resolution of the laser radar and irradiating the laser to the pole 34 having a diameter of 50 mm or more, the reflection time is shorter than the road surface as shown in FIG. because the length W ₂ is short, it can be recognized as pole 34, the towing vehicle 32 may vehicle type identification If it is one pole trailer, including towed vehicle 33. Since detection is more difficult than before and an ultrasonic sensor cannot obtain a reflected wave sufficient to be detected as a vehicle, an auxiliary transmitting / receiving unit is required for recognition (Japanese Patent Laid-Open Publication No. Sho 63-29).
6199). Further, in the method of arranging the optical sensors in the height direction and detecting the number of light-receiving elements that are shielded, the number of light-emitting and receiving devices required for securing the required accuracy is installed.

However, laser light has a convergence property due to its characteristics.
Because the resolution is good, it can be recognized as shown in FIG.
It is possible. Therefore, only one pole trailer is recognized.
It is possible to understand. FIG. 8 shows a vehicle type determination according to another embodiment.
It is a schematic diagram for explaining a device. In this example,
Laser radars 42a and 42b are installed on the road side of road surface 41
Road lanes from the laser radars 42a and 42b, respectively.
Scans the laser beam across the road surface in a direction crossing 41
You. The laser light is reflected irregularly on the road surface 41 and returns.
As shown in FIG. 9, the reflection time of
In the case, it becomes gradually longer from the road side to the center of the lane. Vehicle 4
3 is present, the reflection time from the vehicle 43
Shorter than when reflected from As a result, from the roadside
Distance L to vehicle 43_L, L_RIs subtracted from the lane width L, and L
− (L_L+ L_R), The vehicle width W is calculated. Where L
_RIs the distance from the right roadside to the vehicle 43.

It is possible to accumulate the vehicle portions in time series, recognize the wheel portions from the fluctuations, and measure the vehicle width. FIG. 10 is a schematic diagram for explaining a vehicle type identification device according to another embodiment. In this embodiment, laser radars 52a and 52b and laser light reflecting mirrors 53a and 53b are provided on the road surface 51 on the road side, respectively. Laser radar 52a,
52b, the reflecting mirrors 53a, 53
The laser beam is scanned toward b. The laser light is reflected by the reflecting mirrors 53a and 53b so as to irradiate along a surface perpendicular to the road surface 51 and crossing the lane. Vehicle 54
Is present on the road, the laser light is reflected by the vehicle and passes through reflectors 53a and 53b, and the laser radars 52a and 52b
Return to The distance from the road to the vehicle is calculated from the reflection time at this time, and the vehicle width is calculated by subtracting the distance from the lane width.

In the case of this embodiment, when no vehicle is present, the reflection time becomes longer or the reflection does not return.
Therefore, in calculation, when the reflection time is shorter than the time of reflection and return on the reflection side of the lane, it is determined that the vehicle exists there. The vehicle height can be calculated from the area where the vehicle exists. Further, the distortion of the wheel portion can be determined from the reflection time at the portion in contact with the road surface 51, and the number of axles can be measured.

In order to avoid the influence of interference, the facing positions of the laser reflecting mirrors 53a and 53b are shifted along the lane,
The scanning movement of the laser is shifted. Laser irradiation area when the vehicle in this embodiment is present in FIG. 11 (height direction) - shows the laser beam reflection time, t ₁ corresponds to the distance from the roadside, calculates the vehicle width from the result from the roadside both sides I do.
From the left end (the road surface) to the point laser beam reflected time of the right side is the t ₁ is the vehicle height H _1. When a wheel exists on the scanning surface, the reflection time is the same as that of the vehicle portion, as indicated by a dotted line A.

FIG. 12 is a schematic diagram for explaining a vehicle type discriminating apparatus according to still another embodiment. In this embodiment, bars 62 having a pitch d parallel to the lane are arranged side by side on the road surface 61 in the direction crossing the lane, and the cameras 63a and 63b are suspended above the lane, for example, on the ceiling of a tollgate. are doing. In this embodiment, an image of the road surface immediately below the cameras 63a and 63b is taken, and when the vehicle 64 does not exist,
The lane width and all the bars 62 are taken as an image.
Is present, the bars are hidden by that amount, and the vehicle width can be calculated by counting the number of bars 62 left. For example, as shown in FIG. 13, when the number of the left bars 62 on the left side is n, (n-1) d is the distance from the vehicle 64 to the road side, and similarly, the vehicle 6 on the right side of the lane.
The distance from No. 4 to the road side can be calculated, and the vehicle width is calculated by subtracting this from the lane width.

FIG. 14 is a schematic diagram for explaining a vehicle type discriminating apparatus according to still another embodiment. In this embodiment, bars 72 having a pitch L are provided in a line shape across the lane width in a direction crossing the lane on the road surface 71, and cameras 73a and 73b are installed above the lane as in the case of FIG. Also in this embodiment, the cameras 73a and 73b image the road surface 71 directly below, and when the vehicle 74 does not exist, the bar 72 of the entire lane width is taken as an image. However, when the vehicle 74 exists, the bar 72 corresponds to the vehicle width. Only the bar 72 is hidden.

Now, as shown in FIG. 15, the bar 72 is hidden by the vehicle 74, and the vehicle 74
The number of images for one pitch of the bar 72 is P1, and the number of remaining pixels of the n-th bar 72 is P1.
Assuming that 2, (n-1 + P2 / P1) × L [cm]
The distance from the left road side to the vehicle 74 is calculated. Similarly, since the distance from the right road side to the vehicle 74 can be calculated, the vehicle width can be calculated by subtracting these from the lane width.

FIG. 16 is a schematic diagram for explaining a vehicle type discriminating apparatus according to still another embodiment. In this embodiment, FIG.
2 is further provided with a license plate reading device, and a bar 62 imaged by cameras 63a and 63b.
The vehicle type is determined based on the calculated vehicle width, the size of the license plate read by the license plate reading device, or the vehicle type code.

The license plate reading device is provided with a camera 8 mounted on a column suspended from a ceiling or the like above a road surface 61 ahead of the installation position of the cameras 63a and 63b.
1. A camera 81 captures an image of a front license plate portion of a vehicle 64 at a depression angle of 45 °, similarly to FIG. , Illumination lamps 82a and 82b illuminate the imaging area at night. In the figure, broken lines a and b indicate the range of illumination. In this device, the illumination ranges a and b are illuminated so as to cover the lane width range of the road surface 61 so that the illumination ranges a and b can be used for vehicle width measurement by the cameras 63a and 63b. This eliminates the need to separately install an illuminator for measuring the vehicle width.

FIG. 17 is a schematic diagram for explaining a vehicle type discriminating apparatus according to still another embodiment. In this embodiment, a grid-like paint 92 is formed on the entire road surface 91 in the vehicle width. On the other hand, cameras 93a and 93b are installed above the road surface in front of the grid-like paint 92, and when a vehicle 94 arrives. The number of grids not hidden by the vehicle 94 is obtained from the captured image, the distance between the vehicle 94 and the road side is calculated from the number of grids, and the distance is subtracted from the lane width to calculate the vehicle width.

As in the prior art, when measuring the height of a vehicle from the lateral direction using a photoelectric tube or an ultrasonic sensor, it is difficult to determine the separation between the vehicle and a motorcycle or two motorcycles in parallel. The laser radars 13a and 13 shown in FIG.
In the vehicle type discriminating apparatus using b and 13c, it is possible to separate the vehicle and the motorcycle, and two motorcycles running in parallel. The laser radar can have a resolution of about several centimeters, and the vehicle width W _{BIKE of the} motorcycle 100 in FIG.
1 Car width W _CAR can be measured accurately and motorcycle width W
_BIKE is considerably smaller than the car width W _CAR , so
Separation of automobile and motorcycle is possible. In other words, if the measured width is equal to or less than the predetermined length, it is determined that the motorcycle is a motorcycle,
If the length exceeds a predetermined length, it is determined that the vehicle is a car.

As shown in FIG. 19, the motorcycles 100a, 100a
When 0b runs in parallel, the arrangement of tires is the same as that of an automobile, and an axle meter or a side-illuminated photoelectric sensor cannot recognize that there are two motorcycles. When a laser radar is used to irradiate the road surface with laser light from above, when two motorcycles pass, the road surface is irradiated between the two motorcycles, so the laser light reflection time is as shown in FIG. 19, and the two masses run in parallel. You can see that it is. In the case of the automobile 101, the reflection time is different from that when the road surface is illuminated due to the reflection from the opening roof or the like, so that it can be seen that it is one lump.

Although the above embodiment has been described with reference to the example of vehicle type discrimination at tollgates on toll expressways, the present invention is not limited to toll roads, and is applicable to management in toll areas where cars gather, such as parking lots and ferry boats. Can be widely used.

[0033]

According to the present invention, license plate recognition by the license plate recognition means not only determines the vehicle type based on the plate size or vehicle type code, but also measures the vehicle width, and determines the vehicle type together with the vehicle width. Therefore, the discrimination accuracy can be further improved. In addition, if the imaging means for reading the license plate and the laser radar for measuring the width of the vehicle are installed on the roof, there will be no equipment to be installed on the island, so there is no need to extend the island, etc. Equipment can be introduced.

Further, as in the prior art, when photographing a license plate from the road side, there is a problem of concealment by a front vehicle at the time of traffic congestion. For example, by setting the angle to 45 °, the phenomenon of concealment can be reduced. In addition, if a laser radar is used as the vehicle width measurement means, the distance to the target object in the direction of irradiating the laser beam can be measured from the reflection time, and if it is scanned one-dimensionally, the two-dimensional shape of the target object can be obtained. It is. Therefore, by installing a laser radar on a lane and performing one-dimensional scanning in a direction crossing the lane, it is possible to simultaneously measure the vehicle width and the vehicle height in the cross section of the scanned vehicle.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view illustrating a conventional vehicle type identification device.

FIG. 2 is a schematic perspective view showing an installation example of a vehicle type discriminating apparatus according to one embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a laser radar used in the vehicle type identification device of the embodiment.

FIG. 4 is a diagram illustrating a principle of measuring a vehicle width and a vehicle height using the laser radar.

FIG. 5 is a flowchart for explaining a discriminating processing operation of the vehicle type discriminating apparatus in the embodiment.

FIG. 6 is a schematic diagram for explaining a vehicle type identification device according to another embodiment.

FIG. 7 is a diagram showing an example of a laser irradiation area-laser light reflection time characteristic in the vehicle type discriminating apparatus of the embodiment.

FIG. 8 is a schematic diagram for explaining a vehicle type discriminating apparatus according to still another embodiment.

FIG. 9 is a diagram showing an example of a laser irradiation area-laser light reflection time characteristic in the vehicle type discriminating apparatus of the embodiment.

FIG. 10 is a schematic diagram for explaining a vehicle type discrimination device according to still another embodiment.

FIG. 11 is a diagram showing an example of a laser irradiation area (height direction) -laser light reflection time characteristic of the vehicle type discriminating apparatus of the embodiment.

FIG. 12 is a schematic diagram for explaining a vehicle type discriminating apparatus according to still another embodiment.

FIG. 13 is a diagram illustrating an example of a captured image in the vehicle type identification device of the embodiment.

FIG. 14 is a schematic diagram for explaining a vehicle type discriminating apparatus according to still another embodiment.

FIG. 15 is a diagram illustrating an example of a captured image in the vehicle type identification device of the embodiment.

FIG. 16 is a schematic diagram for explaining a vehicle type discriminating apparatus according to still another embodiment.

FIG. 17 is a schematic diagram for explaining a vehicle type discrimination device according to still another embodiment.

FIG. 18 is a diagram for explaining separation determination of a motorcycle and an automobile by a laser radar in the vehicle type identification device of FIG. 2;

FIG. 19 is a diagram for explaining separation determination of two motorcycles running in parallel by a laser radar in the vehicle type determination device of FIG. 2;

[Explanation of symbols]

 11 Toll booth 12 Ceiling 13a, 13b, 13c Laser radar 14 Camera 18 Vehicle

Continuation of the front page (56) References JP-A-61-22278 (JP, A) JP-A-4-40595 (JP, A) JP-A-3-6799 (JP, A) JP-A-5-172950 (JP) JP-A-6-119597 (JP, A) JP-A-4-354100 (JP, A) JP-A-53-41251 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB G08G 1/015 G01B 11/00 G01S 17/88 G07B 15/00 510 G07C 9/00

Claims (1)

(57) [Claims] 1. A light projecting unit for projecting a laser beam, a scanning unit for scanning the projected laser beam in a direction perpendicular to a vehicle approach direction on a road surface, and a reflection reflected from the road surface or a vehicle. A light receiving unit that receives light, a reflection time calculation unit that calculates the reflection time of the laser light, a reflection time of the laser light when reflected from the vehicle, and a reflection time of the laser light when reflected from the road surface And a vehicle height calculating unit for calculating the vehicle height of the vehicle from the reflection time when the laser light is scanned on the road surface.
Within the scanning range when the reflected light is received for a shorter time
Vehicle width measuring apparatus characterized by comprising a vehicle width calculating unit that calculates a vehicle width based.