JPH10267622A - Object shape detector and vehicle shape detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the driving current of the laser light emitting element of an object shape detector and a vehicle shape detector using laser pulses and to prolong the service life of the element by making the laser light emitting element emit the laser light to the necessary minimum. SOLUTION: An object shape detector which is provided with a laser sensor 2 that emits a laser pulse against a passing object and, at the same time, receives the laser pulse reflected from the object and detects the shape of the object based on the reflecting time of the laser pulse is constituted to detect the position of the object in the passing width direction of the object based on the reflecting time obtained as a result of scanning the object with the laser pulse and to perform the succeeding scanning of the object at the detected position.

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 device for detecting the shape of a passing object by using a laser pulse.
Further, the present invention relates to a vehicle shape detection device for detecting a vehicle shape.

[0002]

2. Description of the Related Art Recently, automatic toll collection has been carried out on expressways and the like. In that case, prior to automatic toll collection, whether the vehicle is a large car, a medium-sized car or a small car is required. It is necessary to determine whether the vehicle is light or not.

As a method of such vehicle type discrimination, a laser pulse is scanned from the laser sensor to the vehicle, the width and height of the vehicle are detected based on the propagation time of the reflected light, and the vehicle type is detected based on the detected information. The decision is made.

[0004]

However, in the laser sensor, since the laser light emitting element is driven with a high output, there is a problem that the power to be supplied is large, and the number of times of light emission is about 33,000 times / second. If it is used constantly, it cannot be used in about 10,000 hours, so it is usually necessary to replace it every year, and there is a problem that the maintenance work for the replacement becomes large. SUMMARY OF THE INVENTION It is an object of the present invention to reduce the driving power and to extend the life of a laser light emitting device by causing the laser light emitting device to emit light with a minimum necessary.

[0005]

According to a first aspect of the present invention, there is provided a laser sensor for scanning a passing object with a laser pulse and receiving the reflected laser pulse, and based on a reflection time of the laser pulse. In the object shape detection device that detects the shape of the object, based on the reflection time by the initial laser pulse scanning for the passing object,
The position of the passing object in the passing width direction is detected, and the subsequent scanning of the passing object is performed at the detected position.

According to the above configuration, when no object passes, the laser pulse is scanned over the entire width of the object to detect the passage of the object, and when the object passes, the laser sensor is provided only at the passing position. Emits a laser pulse. As a result, the number of emitted laser pulses can be reduced, and the life of the laser sensor can be extended.

According to a second aspect of the present invention, a laser sensor is provided for scanning a passing object with a laser pulse and receiving the reflected laser pulse, and detecting the shape of the object based on the reflection time of the laser pulse. In the object shape detection device, the amount of reflected light received by the initial laser pulse scanning of the passing object is detected, and the emission power of the laser light emitting element is changed in accordance with the amount of received light.

According to the above arrangement, for example, when the color of the passing object is white and the amount of reflected light is sufficient, the light emission power is reduced and the light emission amount is reduced. That is, by changing the light emission power between the case where the reflected light amount is sufficiently obtained and the case where the reflected light amount is not obtained, the drive power is reduced, and the life of the laser light emitting element is extended.

The invention according to claim 1 or 2 can be effectively applied to a vehicle shape detecting device (the invention according to claim 3).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an arrangement of a vehicle shape detecting device as an object shape detecting device.

The vehicle shape detecting device 1 includes a laser sensor 2 and
Vehicle width based on data given from laser sensor 2,
The main device 3 detects each vehicle height and detects the shape of the vehicle based on the detected vehicle height.

The laser sensor 2 is attached to a pole 4 at an upper portion of a side of a road surface R reaching a pass gate of a tollgate. As shown in FIG. 2, the laser sensor 2 is provided so as to scan a laser pulse at a position in a range from one side of the vehicle C to a side surface and an upper surface of the vehicle C.

FIG. 3 is a block diagram showing the configuration of the laser sensor 2, and the configuration will be described.

Reference numeral 10 denotes a laser light emitting element. Laser pulses generated by the light emission of the laser light emitting element 10 are successively applied to the polygon mirror 12 at predetermined intervals, and the laser pulse is set by rotating the polygon mirror 12. Angle, and the scanning laser pulse is applied to the road surface R
The reflected laser pulse is reflected by the polygon mirror 12 again and received by the light receiving element 5.

The laser light emitting element 10 is driven by a drive command from the main unit 3, and a start signal is sent to a reflection time propagation time calculation unit 20 at the time of driving. When a laser pulse is received by the light receiving element 5, the light receiving signal is supplied to the propagation time calculation unit 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 gives it to the control unit of the main device 3.

Next, the vehicle width W and the vehicle height H of the main body device 3 will be described.
Each detection method will be described.

FIG. 4 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 traveling direction of the vehicle is calculated based on the propagation time data D of the reflected light obtained from the laser sensor 2. A graph corresponding to a cross section in a direction orthogonal to the above is obtained. The propagation time of the reflected light becomes longer when there is no vehicle C and the light is reflected on the road surface R, and the vehicle C
If it is reflected by the, it is shorter. Based on this figure, 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 D 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 difference time.

Next, an operation control operation of the laser sensor 2 by the main device 3 which is a characteristic configuration of the present invention will be described with reference to an explanatory plan view of FIG. 5 and a flowchart of FIG.

If the vehicle C does not pass, the laser sensor 2 scans a range including the entire width of the road surface R (steps 1 and 2).

When the front end of the vehicle C enters the scanning position of the laser pulse and the reflected light is obtained, the laser pulse from which the reflected light is obtained is detected (step 3), and the next scanning is performed. Width K slightly larger than detection width Ka
The laser pulse scanning at b is performed (step 4). That is, for example, assuming that the reflected light of the vehicle C is obtained in the m-th to n-th laser pulses emitted in one scan, the (m-3) to (n + 3) -th laser pulses will be used in the subsequent scans. Out. Then, the shape of the vehicle is detected based on the propagation time of the reflection time obtained from the vehicle C (step 5). After the detection of the shape of the vehicle C is completed, the process returns to step 1.

As described above, when the vehicle C does not pass, the laser C is scanned by scanning the entire width of the road surface R to detect the vehicle C. When the vehicle C passes, the laser sensor is provided only at the detection position. 2 emits a laser pulse to reduce the number of emitted laser pulses, thereby extending the life of the laser sensor 2.

FIG. 7 shows another embodiment of the operation control operation of the laser sensor 2.

In this embodiment, the light emission power of the laser sensor 2 is controlled in accordance with the amount of light reflected by the color of the vehicle C.

That is, when the front end of the vehicle C enters the scanning position of the laser pulse and its reflected light is obtained, the amount of reflected light is detected (step 1). 10 is to reduce the light emission power (steps 2 and 3). For example, when the color of the passing vehicle C is white, a sufficient amount of reflected light can be obtained. In that case, the light emission power is reduced to reduce the light emission amount, thereby reducing the power supply amount to the laser light emitting element 10. is decreasing. FIG. 8 shows a circuit configuration of a driving unit of the laser light emitting element,
The light emission power is reduced by lowering the light emitting element drive voltage Vh.

As described above, the laser light emitting element 10 is not always operated with a large light emitting power, and the light emitting power is changed between a case where a sufficient amount of reflected light is obtained and a case where the amount of reflected light is not obtained. In addition, the life of the laser light emitting element 10 is extended.

[0027]

According to the present invention, in the object shape detecting device and the vehicle shape detecting device using the laser pulse, the laser light emitting element emits light at the minimum necessary, thereby reducing the driving power. As a result, it is possible to extend the life of the laser light emitting element.

[Brief description of the drawings]

FIG. 1 is an arrangement configuration diagram of a vehicle discrimination device according to an embodiment of the present invention;

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

FIG. 3 is a block diagram of a laser sensor according to an embodiment of the present invention;

FIG. 4 is a diagram showing a propagation time of reflected light corresponding to a vehicle C in a detection area.

FIG. 5 is an explanatory diagram of a scanning state.

FIG. 6 is a flowchart for explaining a scanning operation.

FIG. 7 is a flowchart for explaining a scanning operation in another embodiment.

FIG. 8 is a drive circuit diagram of a laser light emitting device.

[Explanation of symbols]

 2 Laser sensor 3 Main device 10 Laser light emitting element

Claims (3)

[Claims] 1. An object shape detecting device for scanning a passing object with a laser pulse and receiving a reflected laser pulse, and detecting a shape of the object based on a reflection time of the laser pulse. An object shape detection device which detects a position of a passing object in a pass width direction based on a reflection time by an initial laser pulse scanning for the passing object, and performs subsequent scanning of the passing object at the detected position. 2. An object shape detection device, comprising: a laser sensor that scans a passing object with a laser pulse and receives a reflected laser pulse; and detects a shape of the object based on a reflection time of the laser pulse. 1. An object shape detection apparatus, comprising: detecting an amount of reflected light received by an initial laser pulse scan for a laser beam; and changing an emission power of a laser light emitting element according to the amount of received light. 3. A vehicle shape detecting device according to claim 1, wherein the passing object is a vehicle.