JPH06103184B2 - In-vehicle road surface property measuring device - Google Patents

Description

Description: [Industrial field of use] The present invention relates to a device mounted on a vehicle to measure the properties of a road surface.

[Conventional technology]

Road surface properties include a transverse profile, a vertical profile, and cracks on the road surface. Conventionally, these properties were measured by a dedicated device mounted on each different vehicle.

[Problems to be solved by the invention]

For this reason, it takes a lot of time and money to measure the conventional properties, and by using separate dedicated devices that are not related to each other,
Since individual properties are measured, there has been a problem that comprehensive data analysis cannot be performed accurately and easily.

The present invention is intended to solve such conventional problems.

[Means for solving problems]

The present invention provides a laser beam scanning means for scanning a laser beam along a plane orthogonal to the longitudinal axis of a vehicle, an imaging means for imaging a scanning locus of the laser beam on a road surface from obliquely above, and a laser beam scanning means for the laser beam. The difference between the outputs of the first and second light receiving means for receiving the vertically reflected light and the obliquely reflected light from the road surface accompanying the scanning and outputting a signal corresponding to the received level and the output of each of the light receiving means is calculated. A laser beam at a specific scanning position of the laser beam scanning unit is simultaneously projected from the processing unit and the first, second and third positions arranged at a predetermined interval in the front-rear direction of the vehicle toward the road surface. And a ground distance measuring means having different position sensors for receiving the reflected lights of the projected laser beams and detecting the light receiving positions thereof, respectively. The traveling distance measuring means for measuring the traveling distance of the vehicle, the output of the image pickup means, the output of the processing means, and the output of each of the position sensors, information indicating the cross-sectional profile of the road surface, and cracks on the road surface, respectively. Recording means for simultaneously recording the information and the information showing the longitudinal profile of the road surface together with the output of the distance measuring means.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 conceptually shows a laser beam scanning system 10 in an embodiment of the present invention. In this scanning system 10, when the laser beam from the laser projector 13 is incident on the polygon mirror 12 which is rotated in the direction of the arrow by the electric motor 11, the laser beam is emitted from the central separation band 20 laid on the road surface as shown in the figure. Scanning is carried out in the direction of the shoulder, that is, in the direction crossing the road surface.

In the figure, reference numeral 14 indicates a scanning surface of the laser beam, and this scanning surface 14 is orthogonal to the longitudinal axis of the measurement vehicle described later. Further, in this embodiment, the scanning speed of the laser beam is set to 2880 times / second.

FIG. 2 shows a measurement vehicle in which the laser beam scanning system 10 is housed in a casing 21 provided above the driver's seat.

In this vehicle, television cameras 22 and 23 using CCD image sensors and the like are provided on the left and right in the lower front, and optical sensors 24A such as photomultipliers are provided between the cameras. The ground distance detectors 25 and 26 are arranged immediately above the line L connecting the front wheels and the rear wheels and are spaced apart from each other in the front-rear direction of the vehicle, and the tip portion of the casing 21 is further provided. Further, an optical sensor 24B such as a photomultiplier is arranged such that its optical axis is perpendicular to the road surface.

The cameras 22 and 23 and the optical sensor 24A are provided, for example, at an angle of 60 ° with respect to the beam scanning surface 14 in order to capture the trajectory and reflected light of the laser beam on the road surface.

The ground distance detector 25 is an optical fiber cable 25 extending to the laser beam scanning system 10 as shown in FIG.
1 and a position sensor (PSD) 252, the cable 2
The laser beam transmitted through the inside of 51 is projected perpendicularly to the road surface via the lens 253, and the light spot of the beam on the road surface is imaged on the position sensor 252 via the lens 254. Then, the other ground distance detector 25
Is composed of elements 261-264 corresponding to the above elements 251-254.

The distance detector 25 is arranged so that the projection beam is focused at a position Pb which is 1.5 m behind the vehicle from the point Pa where the line L and the laser beam scanning surface 14 intersect, and the distance detector 26 Is 1.5m from the above position Pb toward the rear of the vehicle.
The distance detector 26 is attached so that the projection beam is focused at a position Pb which is distant from the position Pb, and the projection beam is focused at a position Pc which is further 1.5 m away from the position Pb toward the rear of the vehicle. The location has been selected (see Figure 3).

As shown in FIG. 1, a lens 15 and a half mirror 16 are arranged below the polygon mirror 12. Therefore, the laser beam scanned by the polygon mirror 12 passes through the lens 15 and the half mirror 16 and reaches the road surface, and a part of the laser beam is reflected by the upper surface of the half mirror 16.

In this embodiment, when the scanned laser beam is directed to the point Pa, the reflected light from the half mirror 16, that is, the reflected light at the scanning angle θ ₁ is reflected by the optical fibers 251, 261.
It is incident on the base end of. Therefore, the ground distance detectors 25 and 26 project the laser beam toward the road surface every time the scanning angle of the laser beam becomes θ ₁ .

The two mirrors 17 and 18 which are arranged to face each other on the side of the half mirror 16 are provided with a laser beam starting end scanning position (scanning angle 0).
The reflected light of the laser beam from the half mirror 16 is introduced between them to be reflected and propagated, and finally the beam is made incident on the optical sensor 19. Therefore, the optical sensor 19 detects the laser beam each time it is located at the beginning of the scan.

It should be noted that the vehicle is provided with wheels (fifth wheel) (not shown) for measuring travel distance. A traveling distance measuring pulse generator, which will be described later, is attached to this wheel, which outputs one pulse each time the vehicle travels 1 mm in conjunction with the wheel.

FIG. 4 is a block diagram showing the electric circuit of this embodiment. The operation of this embodiment will be described below with reference to FIG.

First, the measurement of the crossing profile of the road will be described.
High Density Video Tape Recorder 30 shown in the figure
When a master clock is input to the controller 31 (hereinafter abbreviated as HD / VTR), the controller 31 outputs a synchronizing signal having a frequency of 60 Hz as shown in FIG. The motor 11 of the system 10 is operated at a constant speed.

When the polygon mirror 12 is rotated by the motor 11, the laser beam is scanned at a cycle of 1/2880, so the optical sensor 19 shown in FIG. 1 outputs a rotational position signal having a frequency of 2.88 KHz. . Then, this position signal is divided by the synchronizing circuit 32 into a signal having a frequency of 60 Hz as shown in FIG. 5B, and the divided output is added as a synchronizing signal to the synthesizing circuit 33 and the signal processing circuit 34 described later. To be

As shown in FIG. 6, when the scanning locus 40 of the beam is formed on the road surface by the scanning of the laser beam, the positions P _{1 to} P on the image pickup surfaces 22a and 23b of the cameras 22 and 23 are set.
The scanning locus in the range of ₂₀₄₈ and the scanning locus in the range of positions P _{2049 to} P ₄₀₉₆ are imaged.

Now, if the vehicle is running at 10km / h,
As shown in Fig. 7, the traveling distance of the vehicle per second is 4.6c.
It becomes m. Since the laser beam is scanned 2880 times while the 4.6 cm vehicle is running, if the readout frequency of the cameras 22 and 23 is 60 Hz, the number of image writings to the camera during this reading cycle is 48. As a result, a plurality of 48 beam scanning loci are drawn in close proximity on the imaging surfaces of those cameras. In this case, the central value of the plurality of images is read at the time of reading the image data described below.

The number of scanning lines of the cameras 22 and 23 is 240 in this embodiment, so that a total of 240 image data in one field are read out from those cameras at a TV rate as shown in FIG. 5 (c). Then, the data read from each of the cameras 22 and 22 is added to the combining circuit 33 as shown in FIG.
It is recorded on the VTR 35 after being subjected to the synthesizing process described later. Note that the image pickup surface of the camera can be temporarily stored and integrated, and the above reading is performed on the image data written on the image surface one field before. Further, the above-mentioned reading process is performed in synchronization with the output signal of the sensor 19.

The synthesizing circuit 33 performs a process of gathering the images read by the cameras 22 and 23 into an image representing a transverse profile, and FIG. 8 shows a mode of this synthesizing process.

Thus, as the vehicle travels, 60 crossing profiles per second are recorded in the VTR, but at the same time the vehicle's mileage is naturally recorded. That is, the pulse generator
A signal of 1 pulse / 1 mm output from 50 is input to a PCM (pulse code modulation) circuit 37 via a correction circuit 36, where it is integrated and coded. From may wish to PCM circuit 37, the travel distance data D _L of the vehicle as shown in FIG. 5 (d) is outputted, which is recorded in the audio track of VTR35. As a result, the VTR 35 sequentially records the crossing profile obtained in each field and each mileage for that profile, that is, the distance from the starting point.

The correction circuit 36 performs processing such as decimation of input pulses in order to correct an error in the traveled distance due to the inclination or slip of the vehicle.

Next, the measurement of cracks on the road surface will be described. 9th
As shown in FIG. 7A, when there is no crack on the road surface irradiated with the laser light, a predetermined amount of scattered light is incident on the optical sensor 24A, but as shown in FIG. When the crack 60 exists on the road surface, the amount of light incident on the sensor 24A decreases due to the so-called shadow effect. Therefore, assuming that FIG. 10 (a) is a rotational position signal output from the optical sensor 19, when a crack exists on the road surface, as shown in FIG. 10 (b), the time when the laser scanning beam passes through the cracked portion. At, the output of the optical sensor 24A decreases, and the position of the signal indicating the decrease in output indicates the position of the crack in the road crossing direction. When the central separation band 20 exists on the scanning locus of the laser beam, the amount of reflected light is increased by the separation band, so that a signal waveform shown by a dotted line appears.

By the way, since the optical axis of the optical sensor 24B is oriented in a direction substantially perpendicular to the road surface, FIG.
In either case of (b), the incident light quantity does not change. Therefore, in this embodiment, the outputs of the sensors 24A and 24B are input to the processing circuit 34, and the difference between those outputs is calculated.
The signal of the difference is recorded on the HD / VTR30 as a video signal. Then, the output pulse of the pulse generator 50 is simultaneously recorded on the audio track of the VTR 30 as traveling distance data in the manner shown in FIG. 5 (f).

Next, the measurement of the longitudinal profile of the road will be described. Now, the laser beam is at a point on the line L shown in FIG.
When scanned up to Pa, the optical fibers 251, 26
Laser light is emitted to the road surface from the ground distance detectors 25 and 26 via 1. As a result, secondary light sources (spots) due to the laser light are formed at the points Pb and Pc on the road surface, and these secondary light sources are imaged on the position sensors 252 and 262 of the detectors 25 and 26 as shown in FIG. To be done. As is well known, the position sensor has a function of outputting the position of the image forming point as an electric signal. Therefore, when the points Pb and Pc at which the secondary light source is formed due to the unevenness of the road surface change vertically, that is, When the ground distances about the points Pb and Pc change, the ground distance signals corresponding to the changes are output from the sensors 252 and 262.

On the other hand, when the laser beam is scanned to the point Pa,
As shown in FIG. 3, the camera 22 captures the image of the point Pa.
Therefore, the ground distance to the Pa point is known by processing this image. That is, the camera 22 also functions as a position sensor that detects the ground distance to the point Pa.

The smoothing circuits 38 and 39 shown in FIG. 4 have the function of averaging the ground distance signals output from the ground distance detectors 25 and 26 with the output pulses of the pulse generator 50, respectively, and averaging them. The signal is coded by the PCM circuit 37 and then V
It is recorded on the TR35 audio track as ground distance data D _B , D _C as shown in FIG. 5 (d).

FIG. 11 exemplifies the recorded contents of the video track and audio track of the VTR35 in one frame of the TV, and shows the value X _A (the value on the screen of the image of the laser beam at the point Pa) shown in the same figure. , Which substantially suggests the ground distance about the point Pa) and the ground distance data D _B , D.
_The disconnection profile is measured from _C and as follows.

That is, as shown in FIG. 12, a line segment connecting points Pa and Pc
By obtaining the distance x formed by the Pb point and calculating σ (estimated value of standard deviation) based on the following formula, the profile in the longitudinal direction of the road surface can be obtained in the same way as when using a so-called 3m profile meter. it can. The data D _L are recorded in the VTR35 as mileage data for the vertical profile is used.

Where χ: measured value, N: number, constant by C ₂ ^* : N, as described above, in this embodiment, the ground distance at the point Pa is obtained based on the image of the camera 22, but In order to obtain the ground distance, each ground distance detector 25,2
A detector similar to 6 may be used.

In this way, data on road cross-section profiles, cracks and profile profiles are recorded in VTRs 30 and 35. This record is transferred off-line and stored in a dedicated image memory, for example, data about cracks is stored in the image memory in the manner shown in FIG. In the figure, the X direction corresponds to the longitudinal direction of the road, the Y direction corresponds to the transverse direction, and the Z direction is data about cracks on the road surface indicated by X and Y addresses. The X-direction address indicates the traveling distance of the vehicle, and the Y-direction address indicates the scanning position of the laser beam. The data stored in this memory is stored in the processing device according to the threshold value L _S shown in FIG.
The value of the crack is determined and the position of the crack is determined based on the data that is equal to or less than the threshold value L _S.

〔The invention's effect〕

 According to the present invention, the following effects can be obtained.

Since three kinds of information on the road crossing profile, cracks, and longitudinal profile are obtained by using the common laser beam scanning means, and these three kinds of information are simultaneously recorded in the recording means together with the traveling distance information. Each recorded information has simultaneity and consistency.

Therefore, comprehensive analysis of road surface characteristics is facilitated and the reliability of analysis results is improved.

Further, since the correspondence relationship between the above-mentioned three types of information and the traveling distance information can be obtained, it is advantageous in specifying a repaired place or the like on the road surface.

Since one laser beam scanning means is shared as an element for obtaining the above-mentioned three kinds of information, the structure can be simplified and the cost can be reduced.

Since the above three types of information can be obtained at the same time, the cost and labor required for measurement can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a perspective view conceptually showing a configuration example of an optical system of a measuring apparatus according to the present invention, FIG. 2 is a perspective view showing a measuring vehicle equipped with the measuring apparatus of the present invention, and FIG. 3 is a ground distance. FIG. 4 is a conceptual diagram showing an arrangement mode of the detection means and a mode of distance measurement, FIG. 4 is a block diagram showing an electric circuit of the measuring device according to the present invention, and FIG. 5 is a time showing an operation of the measuring device according to the present invention. A chart, FIG. 6 is a perspective view showing an aspect of image pickup by a television camera, FIG. 7 is a perspective view showing an image pickup aspect of a television camera in more detail, and FIG. FIG. 9 is a conceptual diagram showing a processing mode, FIG. 9 is a diagram showing a laser beam reflection mode on a road surface, and FIG. 10 is a waveform showing an output waveform of an optical sensor when a crack is present on the road surface. Fig. 11 and Fig. 11 show the recorded contents of the VTR, and Fig. 12 shows the vertical direction Illustrates a technique for obtaining a profile, FIG. 13 is a conceptual diagram showing an embodiment in which to store the data for cracks in the image memory. 10 …… Laser beam scanning system, 12 …… Polygon mirror, 13
…… Rage projector, 16 …… Half mirror, 17,18 …… Mirror, 19 …… Optical sensor, 22,23 …… TV camera, 24A, 2
4B …… Optical sensor, 25,26… Ground distance detector, 251,261 ……
Optical fiber, 252,262 …… Position sensor, 30,35 ……
VTR, 33 …… Synthesis circuit, 34 …… Signal processing circuit, 37 …… PCM
circuit.

Claims (1)

[Claims] 1. A laser beam scanning means for scanning a laser beam along a plane orthogonal to a longitudinal axis of a vehicle, an imaging means for imaging a scanning locus of the laser beam on a road surface obliquely from above, and the laser beam. Difference between the outputs of the first and second light receiving means for respectively receiving the vertically reflected light and the obliquely reflected light from the road surface due to the scanning of 1 and outputting the signal corresponding to the light receiving level, and the light receiving means. And a first and second array arranged at a predetermined interval in the front-back direction of the vehicle.
And means for simultaneously projecting the laser beam at a specific scanning position of the laser beam scanning means toward the road surface from the third position, and the reflected light of these projected laser beams, respectively, and receiving positions thereof. Ground distance measuring means having different position sensors for detecting, mileage measuring means for measuring mileage of the vehicle, output of the image pickup means, output of the processing means and output of the position sensors, respectively. A vehicle-mounted road surface property, comprising: information indicating a cross-sectional profile of the road surface, information indicating a crack on the road surface, and recording means for simultaneously recording the output of the distance measuring means as information indicating a longitudinal profile of the road surface. Detection device.