JPH10170651A - Distance measuring device, position detecting device, shape discriminating device and vehicle discriminating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a distance with high accuracy by detecting a distance of an object on the basis of corrective propagation time of a feflected pulse of the object calculated by a specific procedure. SOLUTION: A reflecting surface 40 of a reference reflecting means is provided on one side of an irradiating window 3 of an inside surface of a case 39 of a laser sensor. Reflecting time of a laser pulse reflected by the reflecting surface 40 with every single scan, substantially becomes time on the basis of circuit operation since a reflecting optical path is very short, and this reflecting time is different in respective laser sensors, and is also different in response to an outside air temperature. That is, the reflecting time of the laser pulse obtained by the reflecting surface 40 with every scanning time, is characteristic of its laser sensor, and becomes real-time. The reflecting time of the reflecting surface 40 is subtracted from on street reflecting time with every scan by a main body apparatus, and substantial on-street reflecting time is calculated. In this way, accurate distance data is obtained on the basis of the substantial on-street reflecting time from which inflience of circuits of the respective laser sensors is reliably removed, and a shape of a vehicle can be also discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a distance measurement, a position detection, and a form discrimination configuration of a vehicle or the like using a laser pulse.

[0002]

2. Description of the Related Art Recently, automatic toll collection has been performed on expressways and the like. In this case, whether the vehicle is a large vehicle or a medium-sized vehicle prior to automatic toll collection. It is necessary to determine whether the vehicle is a small car.

[0003] As a method of such vehicle discrimination, an ultrasonic wave or a laser pulse is irradiated onto a road surface, and the width, length, and height of the vehicle are detected based on the reflection time, and the vehicle is detected based on the detected information. The size of is determined.

[0004]

However, the configuration for performing detection by using the above laser pulse has the following two problems.

The first problem is that the measurement of the reflection time of the laser pulse is not accurately performed. FIG.
Is a block diagram showing a configuration of a laser sensor. First, the configuration will be described.

Reference numeral 1 denotes a light emitting element. Laser pulses generated by the light emission of the light emitting element 1 are sequentially applied to the polygon mirror 2 at predetermined intervals, and the laser pulse is rotated within a set angle by rotating the polygon mirror 2. The scanning laser pulse reaches the road surface through the irradiation window 3, and the reflected laser pulse is reflected by the polygon mirror 2 again through the irradiation window 3 and received by the light receiving element 5. Reference numeral 11 denotes a driving circuit for driving the polygon mirror 2.

The light emitting element 1 is driven by a controller 4
The driving current is monitored by a monitor circuit 8 at the time of driving, and a start signal for each laser pulse is formed by a start signal generating circuit 9 based on the monitor signal. The start signal is supplied to the time difference / voltage conversion circuit 10.

Reference numeral 12 denotes an encoder which detects the rotational position of the polygon mirror 2 and supplies a detection signal to the controller 4.

On the other hand, when a laser pulse is received by the light receiving element 5 and a current is generated, the current signal is
The voltage signal is converted into a voltage signal by the voltage conversion circuit 13 and amplified by the amplifier circuit 15. The stop signal of each laser pulse is formed by the stop signal generation circuit 16 based on the amplified voltage signal.
The signal is supplied to the voltage conversion circuit 10.

In the time difference / voltage conversion circuit 10,
The time difference between the start signal and the stop signal of the corresponding laser pulse was detected and converted into a voltage signal. This voltage signal was converted into a digital signal by the A / D conversion circuit 17, and further processed by the digital processing circuit 18. Thereafter, the data is output from the input / output circuit 19 to the main device 32.

The main unit 32 converts each of the voltage signals into a distance, and based on the distance data, determines the width and width of the vehicle.
The length and height data are obtained, and the body is determined from the data.

In the above configuration, the start signal and the stop signal are formed in the start signal generation circuit 9 and the stop signal generation circuit 16 in accordance with the circuit operation, respectively, at the timing when the light emitting element 1 actually emits light. The time difference between the actual light emission and the light receiving time becomes longer than the actual light emitting and the light receiving time due to the delay from the light receiving time, particularly, the long time required to form the stop signal. This error time is sufficiently large with respect to the actual reflection time of the laser pulse. Therefore, the main unit 32 determines the vehicle body based on data obtained by subtracting the error time from the time difference obtained by the laser sensor.
Conventionally, the error time of the laser sensor is uniform.

However, since the above-mentioned error time is slightly different for each device and also varies depending on the temperature, there is a problem that if the error time is uniformly subtracted as described above, the reflection time cannot be accurately detected. Usually, the error time tends to be shorter at lower temperatures.

The second problem is that the laser pulse is scanned at a predetermined scanning angle with respect to the road by the polygon mirror or the like as described above. Does not match perfectly from time to time, which results in inaccurate object detection locations. That is, the irradiation position of each laser pulse may be slightly deviated from one scan to another, so that a pulse of the same order is not positioned at the same position in each scan, which results in inaccurate position detection and vehicle discrimination. Has not been performed with high accuracy.

The present invention has been made to solve the above problems.

[0016]

According to the first aspect of the present invention, a distance measuring device includes a light emitting means for emitting a laser pulse, and a light receiving means for receiving a reflected laser pulse of the laser pulse from the light emitting means. And, a propagation time detecting means for detecting the propagation time of the reflected laser pulse based on the light emitting timing of the light emitting element and the light receiving timing of the light receiving element, and a reference reflecting means provided near the position of the light emitting element, Corrected propagation of the reflection pulse of the target object by subtracting the propagation time of the reflection pulse at the reference reflection unit detected by the propagation time detection unit from the propagation time of the reflection pulse of the target object detected by the propagation time detection unit Calculating means for calculating time; and distance detecting means for detecting a distance from the target object based on the corrected propagation time from the calculating means. It has a configuration that.

According to the above arrangement, the propagation time of the reflected pulse at the reference reflecting means is subtracted from the propagation time of the reflected pulse of the target object to calculate the corrected propagation time of the reflected pulse of the target object, and based on the corrected propagation time. Since the distance from the target object is detected, the propagation time of the reflected pulse at the reference reflection means, that is, the error time based on the circuit operation is unique to the device and corresponds to the environmental temperature,
Therefore, the corrected propagation time corresponding to the actual distance, that is, the reflection time of the target object can be detected, and the distance can be detected with high accuracy.

The reference reflecting means is formed as a reflecting surface around the irradiation window on the inner surface of the case, for example, and can be easily formed by utilizing the inner surface of the case as described above.

Furthermore, a form discriminating apparatus which can discriminate the form of a vehicle or the like with high accuracy by performing the form discrimination of the target object based on the distance data is obtained (the invention according to claims 3 and 4).

According to a fifth aspect of the present invention, the position detecting device comprises: a light emitting means for emitting a laser pulse; a scanning means for scanning a laser pulse from the light emitting means; and a reference reflecting means for the scanned laser pulse. Light receiving means for receiving a reflected laser pulse of the laser pulse scanned by the scanning means; and detecting the propagation time of the reflected laser pulse based on the light emitting timing of the light emitting element and the light receiving timing of the light receiving element. Time detecting means, and position detecting means for detecting the position of the target object by specifying the reflection position of the reflected pulse on the target object determined from the propagation time based on the reflected laser pulse in the reference reflecting means. Configuration.

According to the above configuration, the position of the target object is detected by specifying the reflection position of the reflected laser pulse based on the reflected laser pulse in the reference reflection unit. Even in the case where there is a slight shift for each scan, the detection and determination of the vehicle can be performed with high accuracy without any trouble.

The reference reflecting means is formed as a reflecting surface around the irradiation window on the inner surface of the case, for example, and can be easily formed by using the inner surface of the case as described above.

Further, a form discriminating apparatus which can discriminate the form of a vehicle or the like with high accuracy by performing the form discrimination of the target object based on the position data is obtained (the invention according to claims 7 and 8).

[0024]

FIG. 1 shows the arrangement of a vehicle discriminating device. A vehicle discriminating device 30 includes three laser sensors 31.
a, 31b, 31c and their laser sensors 31a, 3a
A main body device 32 that detects a vehicle width, a vehicle length, and a top surface shape of a vehicle based on a time difference signal given from each of 1b and 31c, and further determines the vehicle shape based on them.
Consists of

Each of the laser sensors 31a, 31b and 31c is attached to, for example, a bar 34 provided so as to cross the road surface R leading to a passing gate of a tollgate so as to be sequentially moved back and forth in the traveling direction. Is from the road surface R on one side of the vehicle C to the side surface of the vehicle C,
The central laser sensor 31b is located in the range extending to the upper surface of the vehicle C.
The other laser sensor 31c is provided so as to scan the laser pulse 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.

FIG. 2 shows the configuration of the irradiation window 3 of the laser sensor 31a. The configuration of the other parts of the laser sensor 31a is the same as that of the conventional example shown in FIG. In the configuration of FIG. 8, the light emitting element 1 propagates light emitting means, the polygon mirror 2 performs scanning means, the light receiving element 5 propagates light receiving means, and the start signal generation circuit 9, the stop signal generation circuit 16, and the time difference / voltage conversion circuit 10 propagate. The time detecting means is constituted.

On one side of the irradiation window 3 on the inner surface of the case 39 of the laser sensor 31a, there is provided a reflecting surface 40 consisting of a mirror surface as reference reflecting means, and the scanning of the laser pulse extends over this reflecting surface 40. This is performed at an angle larger than the angle corresponding to the opening width of the irradiation window 3.

As described above, the reflection surface 40 is provided, so that the reflection time of the laser pulse reflected by the reflection surface 40 for each scan is the same as the operation of the laser sensor described in the conventional example. can get. This reflection time is substantially a time based on the circuit operation (corresponding to the error time in the description of the conventional example) because the reflection light path is very short. This reflection time differs depending on the variation in the device manufacturing of each laser sensor. Even the same laser sensor differs depending on the outside air temperature. That is, the reflection time of the laser pulse obtained by the reflection surface 40 at each scanning time is unique to the laser sensor and real-time.

The reflection time by the reflection surface 40 is obtained by the laser sensor 31a in addition to the reflection time on the road for each scan, so that the main unit 32 as the calculating means, the distance detecting means, or the position detecting means performs scanning. By subtracting the reflection time of the reflecting surface from the road reflection time for each time, the actual road reflection time obtained by subtracting the time based on the circuit operation is calculated.

FIG. 3 is a graph showing the reflection time corresponding to the temperature, where T1 is the reflection time at the reflection surface at low temperature, and T1 is the reflection time.
2 is the reflection time on the reflecting surface at high temperature, T3 is the reflection time on the road at low temperature, T4 is the reflection time on the road at high temperature, and the real reflection time of T3-T1 is obtained at low temperature. At a high temperature, a substantial road reflection time of T4-T2 is obtained.

Further, the main device 32 detects a distance corresponding to each of the substantial road reflection times. In this manner, the main apparatus 32 detects the distances corresponding to the substantial road reflection times in which the effects of the circuits of the laser sensors 31a, 31b, and 31c are reliably removed. Accurate distance data is obtained based on the distance data, and the width of the vehicle C is detected based on the distance data.
A small discrimination is made.

FIG. 4 is a diagram for explaining the vehicle discriminating operation, in which each of the laser sensors 31a, 31b, 31c has one
Lines L1, L2, L3 along the distance data (reflection time) obtained by scanning are connected to form a line L. The line L corresponds to a cross-sectional configuration in a direction orthogonal to the traveling direction of the vehicle C. Then, on the line L, the measurement distance decrease start position X is the one end position of the vehicle, the measurement distance increase end position Y is the other end position of the vehicle C, and the distance Z between the X position and the Y position is The distance H corresponds to the height of the vehicle. Further, the detection time of the vehicle C is obtained from the distance data based on the central laser sensor 31b, the vehicle length is detected from the product of the detection time and the speed of the vehicle C, and the distance data in the traveling direction of the upper surface of the vehicle is obtained from the distance data. Detect the morphology.

Based on the respective detected data, the vehicle C is determined to be large, medium, small, bus, trailer or the like, and the determined data is given to an automatic toll collection device or the like.

In the above-described vehicle determination, as described below, the reflection signal on the reflection surface 40 is used as a reference signal, thereby detecting the vehicle width more accurately.

The position on the road where the reflected laser pulses corresponding to the respective distance data forming the line L in FIG. 4 are obtained is accurately specified based on the scanning order from the reflected laser pulses obtained on the reflecting surface 40, By accurately specifying the one end position and the other end position of the vehicle, the vehicle width, which is the distance therebetween, is accurately detected. That is,
The laser sensors 31a, 31b, 31c are fixedly arranged on the road, and the laser sensors 31a, 31b, 3c
Since the reflection surface 40 provided on the inner surface of the case 39 of FIG. 1c is at a fixed position with respect to the road position, the reflection laser pulse on the road in a predetermined scanning order from the reflection laser pulse obtained by the reflection surface 40 is shifted from the predetermined position on the road. It is obtained.

FIG. 5 is a diagram showing the state of laser pulse irradiation on the reflecting surface 40. In scanning, laser pulses P1, P2, and P3 are irradiated on the anti-slope surface 40, and as shown in FIG. 5, the laser pulse P2 is reflected. When the light is irradiated so as to exactly match the surface 40 and the set maximum reflected light amount is obtained in the reflected light of P2, it is determined that the reflection surface 40 is located at the irradiation position of the laser pulse P2. Also, as shown in FIG. 6, when the laser pulses P1 and P2 are applied to the position shifted from the reflection surface 40, and the set maximum reflected light amounts cannot be obtained in both the laser pulses P1 and P2, the laser pulses P1 and P2 It is determined that there is a reflective surface 40 between the laser pulses P1 and P2, and the accurate position of the laser pulses P1 and P2 with respect to the reflective surface 40 is detected from the ratio of the reflected light amounts of the laser pulses P1 and P2. In this manner, the position of the laser pulse corresponding to the reflection surface 40 is determined at the time of scanning, so that the position of the road surface of the laser pulse of a predetermined order is also specified, and accurate position detection is performed.

As described above, even if the irradiation position is slightly shifted for each scan by the polygon mirror 2 and the pulse of the same order is not irradiated to the same position in each scan, the detection and determination of the vehicle C can be performed without any problem. Done to precision.

In the above embodiment, the reflection surface 40 is separately provided on the inner surface of the case 39.
The reflection surface may be provided by making the inner surface of 9 itself a mirror surface, and in that case, the periphery is covered with a mask so that the reflection surface position is provided at a predetermined position and a predetermined size. Is also good.

Next, the operation of the laser sensors 31a, 31b, 31c of the main device 32 used in response to a change in the conversion characteristic of the time difference / voltage conversion circuit 10 will be described.

Laser sensors 31a, 31b, 31c
As shown in FIG. 7, the conversion characteristics of the time difference / voltage conversion circuit 10 may change with a change in temperature. In this case, the laser sensors 31a, 31b, 3
If the distance is detected by converting the voltage signal obtained from the 1c side at a uniform conversion rate, there arises a problem that an accurate distance cannot be detected. Therefore, in the main device 32 of this embodiment,
The voltage signals from the laser sensors 31a, 31b and 31c are monitored based on the reflection time of the laser pulse on a road surface that is a fixed distance, and the voltage signals do not reach a predetermined value and the conversion characteristics of the time difference / voltage conversion circuit 10 change. When the distance is recognized, the distance is accurately detected by converting at a change rate corresponding to the change. If the change in the conversion characteristic of the time difference / voltage conversion circuit 10 becomes too large, the laser sensors 31a, 31b, 31c are replaced.

[0041]

According to the present invention, in distance detection using a laser pulse, the reflection time of the target object can be detected without being affected by the circuit operation of the device, and the distance detection can be performed with high accuracy. Accordingly, detection and determination of the vehicle and the like are performed with high accuracy.

Further, even when the irradiation position of the scanning means such as a polygon mirror is slightly shifted for each scan, the detection and determination of the vehicle or the like can be performed with high accuracy without any trouble.

[Brief description of the drawings]

FIG. 1 is a layout diagram of a vehicle discriminating apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an irradiation window portion in the embodiment.

FIG. 3 is an explanatory diagram of a propagation time.

FIG. 4 is a diagram for explaining a vehicle discriminating operation.

FIG. 5 is a diagram showing an irradiation state of a laser pulse on a reflection surface.

FIG. 6 is a diagram showing an irradiation state of a laser pulse on a reflection surface.

FIG. 7 is a conversion characteristic diagram of a time difference / voltage conversion circuit.

FIG. 8 is a block diagram illustrating a configuration of a laser sensor.

[Explanation of symbols]

 Reference Signs List 1 light emitting element (light emitting means) 5 light receiving element (light receiving means) 9 start signal generating circuit (propagation time detecting means) 10 time difference / voltage conversion circuit (propagating time detecting means) 16 stop signal generating circuit (propagating time detecting means) 32 main body Equipment (calculating means, distance detecting means) 40 Reflecting surface (reference reflecting means)

Claims (8)

[Claims] A light emitting unit that emits a laser pulse; a light receiving unit that receives a reflected laser pulse of the laser pulse from the light emitting unit; a light emitting unit that emits a laser pulse based on a light emitting timing of the light emitting element and a light receiving timing of the light receiving element. Propagation time detection means for detecting the propagation time of the reflected laser pulse, reference reflection means provided near the position of the light emitting element, and the propagation time of the reflection pulse of the target object detected by the propagation time detection means Calculating means for subtracting the propagation time of the reflected pulse at the reference reflecting means detected by the propagation time detecting means to calculate a corrected propagation time of the reflected pulse of the target object; and A distance measuring device, comprising: distance detecting means for detecting a distance from a target object. 2. A case is provided with an irradiation window for irradiating a laser pulse from the light emitting means, and a reflection surface as the reference reflection means is formed at a position on the inner surface of the case around the irradiation window. The distance measuring device as described. 3. The form discriminating apparatus according to claim 1, further comprising discriminating the form of the target object based on distance data from the distance detecting means. 4. The vehicle type determination device according to claim 3, wherein the target object is a vehicle. 5. A light emitting unit that emits a laser pulse, a scanning unit that scans a laser pulse from the light emitting unit, a reference reflecting unit for the scanned laser pulse, and a laser beam that is scanned by the scanning unit. Light receiving means for receiving the reflected laser pulse; propagation time detecting means for detecting the propagation time of the reflected laser pulse based on the light emitting timing of the light emitting element and the light receiving timing of the light receiving element; and reflection at the reference reflecting means. And a position detecting means for detecting a position of the target object by specifying a reflection position of the reflection pulse on the target object determined from the propagation time based on the laser pulse. 6. A case is provided with an irradiation window for irradiating a laser pulse from said light emitting means, and a reflection surface as said reference reflection means is formed at a position on the inner surface of the case around the irradiation window. The position detecting device as described in the above. 7. The position detecting device according to claim 5, further comprising: determining the type of said target object based on position data from said position detecting means. 8. The form discriminating apparatus according to claim 7, wherein the target object is a vehicle.