JP3399282B2 - Object shape detection device and vehicle shape detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object shape detecting apparatus for detecting the shape of an object passing by using a plurality of laser pulses, and further to a vehicle shape detecting apparatus for detecting the shape of a passing vehicle.

[0002]

2. Description of the Related Art Recently, automatic toll collection has started to be carried out on expressways, in which case the vehicle is a large vehicle, a medium-sized car or a small vehicle prior to the automatic toll collection. It is necessary to determine whether the vehicle is light or not.

As such a method of discriminating a vehicle type, a plurality of laser sensors are sequentially provided along the passing direction of an object,
Laser pulses are scanned from different directions from both sides and above the object from each, and the width, length, and height of the vehicle are detected by the propagation time of the reflected light, and the vehicle type is discriminated based on the detected information. I try to do it.

In the above description, the respective laser sensors are sequentially provided in the passing direction of the object because the vehicle speed is detected from the distance between the laser sensors based on the detection deviation time of each laser sensor and the detection time when passing the vehicle. This is to detect the vehicle length from the product of the vehicle speed. The width and height of the vehicle can be directly detected from the propagation signal of the reflected light.

[0005]

However, the high-power laser light emitting device used in the laser sensor is
Its life is about 33,000 times / second, and if it is constantly used for light emission, it cannot be used for about 10,000 hours, and it is usually necessary to replace it every year. Therefore, when a plurality of laser sensors are used as in the above-mentioned conventional example, there is a problem that maintenance work for replacing the laser sensors becomes large.

It is an object of the present invention to extend the life of the laser light emitting element by making the laser light emitting element emit light in the minimum necessary amount and to improve the maintainability of the object shape detecting device and the vehicle shape detecting device. To do.

[0007]

The invention according to claim 1 of the present invention is provided sequentially along the passing direction of an object, and each scans the object with a laser pulse from a different direction, and the reflected laser pulse It is an object shape detection device that has a plurality of laser sensors that receive light and outputs the light reception signal, and that detects the shape of the object based on the light reception signals. When the passage of an object is detected on the basis of the light reception signal of the laser sensor, the laser sensor of the next stage and thereafter is operated.

According to the above construction, the laser pulse is emitted from each of the laser sensors of the next stage and thereafter only when the passage of the vehicle C is detected based on the laser sensor of the front stage. The number of laser pulses emitted from the laser sensor is minimized, and the life of those laser sensors is improved.

Particularly, as in the second aspect of the invention, the laser sensor at the front stage is always scanned at a low scanning density, and is scanned at a high scanning density when the passage of the object is detected. The number of laser pulses emitted from the laser sensor can also be reduced, which makes it possible to extend the life of all the laser sensors.

According to a third aspect of the present invention, the objects are sequentially provided along the passage direction of the object, and each of them scans the object with a laser pulse from a different direction, receives the reflected laser pulse, and outputs the light reception signal. An object shape detection device that includes a plurality of laser sensors and detects the shape of an object based on the received light signal, in the scanning cycle corresponding to the detection time difference of the object between the laser sensor at the front stage and the laser sensor at the next stage. Each laser sensor is scanned.

According to the above construction, when the detection time difference is long, that is, when the moving speed of the vehicle is slow, the scanning pulse is unnecessarily emitted by increasing the scanning period to reduce the number of scannings per hour. Is avoided. Even if the number of scans per hour is reduced, the moving speed of the vehicle is slowed down, so the number of scans for one vehicle is not reduced, and therefore the shape detection is not affected.

When the number of scans is changed, for example, when the laser pulse scanning is performed by using a polygon mirror, the reflective surface of the polygon mirror is selectively used to perform the scanning without any trouble. (The invention according to claim 4).

An object shape detecting device according to any one of claims 1 to 4,
A vehicle shape detection device is obtained by being configured to detect the shape of a vehicle as an object (the invention according to claim 5).

[0014]

FIG. 1 shows the overall arrangement of a vehicle shape detecting device as an object shape detecting device.

The vehicle shape detecting device 1 includes three laser sensors 2a, 2b and 2c, and these laser sensors 2a, 2b, and
2c, the vehicle width, the vehicle height, the number of axles, and the vehicle length are detected based on the data respectively given, and the main body device 3 for detecting the shape of the vehicle by them is detected.

Each of the laser sensors 2a, 2b and 2c is sequentially attached in the traveling direction to a bar 5 provided so as to cross a road surface R leading to a passage gate of a toll gate. Then, as shown in FIGS. 2 and 3, one laser sensor 2a extends from the road surface R on one side of the vehicle C to the side surface and the upper surface of the vehicle C, and the central laser sensor 2b extends to the upper surface of the vehicle C. In the range, the other laser sensor 2c scans the laser pulse in a range extending from the road surface R on the other side of the vehicle C to the side surface and the upper surface of the vehicle C, and further to the positions which are forward and backward in the traveling direction of the road surface R. It is provided.

FIG. 4 is a block diagram showing the structure of the laser sensors 2a, 2b, 2c, and the structure will be described.

Reference numeral 10 denotes a laser light emitting element. Laser pulses generated by the laser light emitting element 10 are sequentially irradiated to a polygon mirror 12 at predetermined intervals, and the polygon mirror 12 is rotated to set the laser pulse. Scanning is performed within an angle, the scanning laser pulse reaches the road surface, and the reflected laser pulse is again reflected by the polygon mirror 1.
It is reflected by 2 and received by the light receiving element 5.

The laser light emitting element 10 is driven by a drive command from the main body device 3 side, and at the time of driving, a start signal thereof is sent to the reflection time propagation time calculating section 20. When the light receiving element 5 receives the laser pulse, the light receiving signal is given to the propagation time calculating section 20 as a stop signal. Then, the propagation time calculation unit 20 calculates the detection time difference between the start signal and the stop signal of the corresponding laser pulse, that is, the propagation time of the reflection time, and supplies it to the control unit of the main body device 3.

Next, a method of detecting the vehicle width W, the vehicle height H, the number of axes B, and the vehicle length L in the main body device 3 will be described.

FIG. 5 is a diagram showing the propagation time of the reflected light corresponding to the vehicle C in the detection area irradiated with the laser pulse, and the propagation time data D1 of the reflected light obtained from each of the laser sensors 2a, 2b, 2c. , D2, D3, a graph corresponding to the cross section in the direction orthogonal to the traveling direction of the vehicle can be obtained. The propagation time of the reflected light is longer when the vehicle C is absent and is reflected on the road surface R, and is shorter when the vehicle C is reflected. Based on this figure, first, the vehicle width W and the vehicle height H are detected.

That is, the vehicle width W is between the edges E1 and E2 in the data D1 and D2 of the vehicle C, and the difference between the reflection time on the road surface R and the reflection time on the upper surface of the vehicle C corresponds to the vehicle height. The vehicle height H is calculated from the time difference.

When detecting the vehicle length L, first, the vehicle speed V is calculated as follows. FIG. 6 shows laser sensors 2a and 2
Data D1, D2 associated with passing of vehicles b, 2c,
The detection timing of D3 is shown, and the laser sensors 2a, 2
Since b and 2c are provided at positions that are sequentially located in front of and behind in the passage direction, the detection timings thereof are sequentially arranged. Then, the first vehicle speed of the vehicle is detected by dividing the distance F1 (FIG. 3) between the laser sensor 2a and the laser sensor 2b and the scanning position by the detection deviation time Z1 between the laser sensor 2a and the laser sensor 2b. The laser sensor 2b and the laser sensor 2c are detected at the detection deviation time Z2 between the sensor 2b and the laser sensor 2c.
The second vehicle speed of the vehicle is detected by dividing the distance F2 (FIG. 3) between the scanning position and the scanning position, and the average vehicle speed is defined as the vehicle speed V. In this way, the vehicle speed can be accurately detected even if the vehicle is accelerating or decelerating in the passing area. Then, from the product of the detection time T when the vehicle C passes by the laser sensor 2b at the center and the vehicle speed V, the vehicle length L
To detect.

The number of axes B is detected based on the form of the data D1 and D3 shown in FIG. That is, FIG. 5 shows a case where the laser pulse is scanned at the tire position of the vehicle C, while FIG. 7 shows a case where the laser pulse is scanned at a position where the vehicle tire is not present.

When there is no tire, the reflected light from the tire cannot be obtained, so the reflected light from the vehicle body is interrupted at the lower edge G position of the vehicle body side, and then the reflected light from the road surface R is obtained. The propagation time of the reflected light also sharply decreases at the G position. Therefore, the number of times the passing vehicle obtains the data D1 and D3 as shown in FIG. 7 is detected, and this is detected as the number of axes B.

Further, the fact that the vehicle C is a towing vehicle is detected based on the form of the data D2 portion in FIG. FIG. 5 shows the case where the laser pulse is scanned at a position other than the pulling pole P, while FIG. 8 shows the case where the laser pulse is scanned at the pole P position. That is, in the portion where the pole P exists, the reflected light of the vehicle C can be obtained only in the portion where the pole P exists, so the data D2 portion becomes as shown in FIG. Therefore, when the passing vehicle obtains the data D2 as shown in FIG. 8, it can be detected as a towing vehicle.

Next, the operation control operation by the main body device 3 of each laser sensor 2a, 2b, 2c, which is a characteristic configuration of the present invention, will be described with reference to the plan view of FIG. 9 and the flowchart of FIG.

When the vehicle C is not passing, the laser pulse is scanned only by the laser sensor 2a (step 1), and the driving pulse is thinned out in some cases, so that three pulses are obtained in one scanning. Laser pulse is emitted. When the vehicle C reaches the portion corresponding to the laser sensor 2a and the passage of the vehicle is detected from the propagation time of the reflection time (step 2), the number of laser pulses emitted in one scan of the laser sensor 2a is increased to one. (Step 3), and further laser sensor 2b and laser sensor 2
Also in c, scanning of the laser pulse is started (step 4). At that time, the number of laser pulses emitted from each of the laser sensors 2b and 2c is the same as the increased number of emission from the laser sensor 2a. Then, the shape of the vehicle is detected as described above based on the propagation time of the reflection time obtained by each of the laser sensors 2a, 2b, 2c (step 5). After the detection of the vehicle shape is completed, the process returns to step 1.

As described above, first, laser pulses are emitted from the laser sensors 2b and 2c only when the vehicle C passes, and the laser sensor 2a is also required for shape detection only when the vehicle passes. Since the laser pulses are emitted, the number of laser pulses emitted by each of the laser sensors 2a, 2b, 2c is minimized, and the life of the laser sensor can be extended.

FIG. 11 shows a simplified diagram of a modification of the above embodiment.

In this modified example, the laser sensors 2a, 2
Each of b and 2c is attached to an endless chain 40, and the position of the laser sensors 2a, 2b, and 2c can be shifted by operating the endless chain 40 by a motor 41. In the above embodiment, since only the laser sensor 2a is constantly used and its life is shortened,
In this modified example, the positions of the laser sensors 2a, 2b, 2c are shifted every predetermined period, so that the respective laser sensors 2a, 2b, 2c are made to have a uniform service life, whereby the laser sensors 2a, 2b, 2c are made uniform. The maintenance time is further improved by using the same replacement time. The shift of the laser sensors 2a, 2b, 2c is automatically performed by controlling the motor 41 by the main body device 3.

FIG. 12 is a flow chart showing another embodiment of the operation control operation of the laser sensors 2a, 2b, 2c.

In this embodiment, the scanning number of each of the laser sensors 2a, 2b and 2c is increased / decreased according to the speed of the vehicle. Normally, that is, the passing vehicle is
For example, when the vehicle is traveling at a speed of 20 km / hour or more, each laser sensor scans at a predetermined dense scanning interval (scanning cycle 2.5 ms) (step 1), and the speed of the passing vehicle is reduced due to traffic congestion. Is decreased, and the detection deviation time Z1 between the laser sensor 2a and the laser sensor 2b decreases.
When the speed of the passing vehicle detected based on the above is less than the set value of 20 km / hour (step 2), the scanning period of each laser sensor 2a, 2b, 2c is doubled to halve the number of scanning. , The scanning interval is made sparse (step 3). When the number of scans is halved in this way, as shown in FIG. 13, by using only every other reflecting surface 12a in the polygon mirror 12, the scanning operation can be performed without any trouble.

As described above, when the traveling speed of the vehicle is slow due to traffic congestion or the like, unnecessary scanning of the laser pulse is avoided by reducing the number of scans. Even if the number of scans per hour is reduced, the moving speed of the vehicle is slowed down, so the number of scans for one vehicle is not reduced, and therefore the shape detection is not affected at all.

[0035]

According to the present invention, the laser light emitting element can be used for light emission at the minimum necessary for detection, which makes it possible to prolong the life of the laser light emitting element, and to detect the object shape detecting device and the vehicle shape detecting device. The maintenance of the device can be improved.

[Brief description of drawings]

FIG. 1 is an overall layout configuration diagram of a vehicle detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a scanning state of a laser pulse to a vehicle.

FIG. 3 is a diagram showing a scanning state of laser pulses to a vehicle.

FIG. 4 is a block configuration diagram of a laser sensor according to an embodiment of the present invention.

FIG. 5 is a diagram showing a propagation time of reflected light corresponding to a vehicle C in a detection area.

FIG. 6 is a diagram showing a propagation time of reflected light corresponding to a vehicle C in a detection area.

FIG. 7 is a diagram showing a propagation time of reflected light corresponding to a vehicle C in a detection area.

FIG. 8 is a diagram showing a propagation time of reflected light corresponding to a vehicle C in a detection area.

FIG. 9 is an explanatory plan view of laser pulse scanning.

FIG. 10 is a flowchart for explaining the operation.

FIG. 11 is an explanatory diagram of a modification example of mounting the laser sensor according to the first embodiment.

FIG. 12 is a flowchart for explaining the operation in another embodiment.

FIG. 13 is an explanatory diagram of scanning with a polygon mirror.

[Explanation of symbols]

2a Laser sensor 2b Laser sensor 2c laser sensor 3 Main equipment 10 Laser emitting element 12 polygon mirror

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Claims (5)

(57) [Claims] 1. An object is sequentially provided along a passing direction of an object,
An object shape that scans laser pulses from different directions on the object and that has a plurality of laser sensors that receive the reflected laser pulse and output the received light signal, and detect the shape of the object based on the received light signal It is a detection device, and only the laser sensor at the front stage is always operated, and when passage of an object is detected based on the light reception signal at the laser sensor at the front stage, the laser sensor at the next stage or later is operated. Object shape detection device. 2. The object shape detecting apparatus according to claim 1, wherein the laser sensor at the frontmost stage is always scanned at a low scanning density, and is scanned at a high scanning density when the passage of the object is detected. 3. Sequentially provided along the passing direction of the object,
An object shape that scans laser pulses from different directions on the object and that has a plurality of laser sensors that receive the reflected laser pulse and output the received light signal, and detect the shape of the object based on the received light signal An object shape detection device, which is a detection device, wherein each laser sensor is scanned in a scanning cycle corresponding to a difference in detection time of an object between the laser sensor at the front stage and the laser sensor at the next stage. 4. The object detecting apparatus according to claim 3, wherein the laser pulse scanning is performed by using a polygon mirror, and the reflecting surface of the polygon mirror is selectively used. 5. A vehicle shape detecting apparatus according to claim 1, wherein the object shape detecting apparatus is configured to detect the shape of a vehicle as an object.