JPS6293607A - Method for measuring cross-sectional shape of road surface - Google Patents

Abstract

PURPOSE:To make it possible to automatically measure road surface information at a high speed even in the daytime, by irradiating a road surface with laser beam and introducing the reflected beam from said road surface into a semiconductive beam spot position detecting element through an optical filter of which the center frequency is same to the frequency of laser beam. CONSTITUTION:Laser beam from a laser beam generator 10 is allowed to scan and irradiated a road surface R by a scanner 2 and the reflected beam thereof is received by a photo receiver 14. An optical filter 18 of which the center frequency is same to the frequency of laser beam is provided on the photo- receiver 14 and the beam passing through the optical filter 18 comes incident on a plurality of semiconductive beam spot position detecting elements 20 to be converted to an electric signal. The outputs of the semiconductive beam spot position detecting elements 20 are respectively inputted to a plurality of electric filters 24 each having center frequency corresponding to a scanning cycle and the outputs of the electric filters 24 are successively taken out to obtain the information of the cross-sectional shape of the road surface R by a signal processing unit 30.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a method for measuring cross-sectional shapes of road surfaces such as road ruts, and in particular, to a method for continuously detecting information (signals) on cross-sectional shapes of road surfaces without being affected by natural light. , concerning methods for obtaining information suitable for automatic measurements.

[Conventional examples and their problems] Conventional methods for measuring the cross-sectional shape of road surfaces (hereinafter referred to as road ruts) have been to create dark lines on the road surface using a strobe light source, or to create dark lines on the road surface using laser light. The BuJ method has been proposed in which a bright line is formed, this dark line or bright line is photographed with a pulse camera or a television camera, and road ruts are measured based on the information obtained by the photographing.

However, under natural light, it is impossible to distinguish between dark lines and bright lines, so it is impossible to perform the entire ηtr+regular work. Therefore, there was a problem that measurement work was limited to nighttime. Furthermore, even when working at night, headlights from oncoming or following vehicles reduce the contrast between dark or bright lines and other parts, making measurement impossible.

[Objective] The present invention provides a method that allows detection of rut information during daytime work without being affected by natural light.

An object of the present invention is to provide a method for automatically and rapidly detecting rutting information through daytime measurement work and obtaining rutting information optimal for automatic measurement.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

Although the method according to the present invention is a method for automatically obtaining road rut information using a device mounted on a vehicle, the information obtained in this way may be processed within the vehicle-mounted device, Alternatively, it goes without saying that it may be processed at another location after traveling.

As shown in FIG. 1, the optical scanner 12 transmits a laser beam from a laser beam generator 1O in a direction substantially perpendicular to the traveling direction of the vehicle at a predetermined interval (from a light point PI to a light point PN). Scan the road surface R by swinging it. The optical scanner 12 is, for example, a polyhedron having a plurality of light reflecting surfaces, and is a known device that rotates to scan a light point PO formed on the road surface R with a laser beam.

The light receiver 14 includes a condensing lens 16, an optical filter 18, and a light spot position detector 20, and is provided in the vehicle so as to have a predetermined angle with respect to a horizontal plane. As shown in FIG. 2, the light spot position detector 20 includes a plurality of semiconductor light spot position detection elements D-1 to DN (N pieces). A semiconductor detection element is an element whose resistance value changes depending on the position of a light spot on the semiconductor, and therefore, the position of the light spot on the element is specified based on the change in resistance value. Note that this semiconductor light spot position detection element itself is well known.

The optical filter 18 is a filter having the same center frequency as the frequency of the projected laser light.

Therefore, only the laser light can be obtained from the output of the optical filter 18 (of course, depending on the laser light used, natural light having the same wavelength as the laser light may be included).

After passing through the condensing lens 16 and the optical filter 18, the bright lines (P1 to PN) of the laser beam on the road surface R are displayed as bright lines ff1 (PI-PN) on the light spot position detector 20, as shown in FIG. )
! , : Appears as a corresponding optical image (pi' to PN'). Therefore, each of the plurality of semiconductor detection elements outputs an electric signal indicating the position of the light spot imaged thereon.

The electrical outputs from the semiconductor detection elements D-l to D-N are transmitted through the next stage amplifiers 22 (1) to 22 (N), respectively.
It is input to electric filters 24(1) to 24(N). The electric filter 24 is a bandpass filter having a center frequency equal to the scanning frequency of the laser beam that scans the road surface R. Therefore, the optical filter 18 allows only the laser beam to pass through, and the electrical filter 24 removes electrical signals other than the scanning frequency (and frequencies near it), so noise (
(including natural light) can be eliminated to a negligible degree. The outputs (analog) from the plurality of semiconductor detection elements are sequentially input to an analog-to-digital (A/D) converter 28 by a signal switcher (multiplexer) 26 in the first stage and converted into corresponding digital signals. Ru. The output of the A/D converter 28 is input to a signal processing device 30. The signal processing device 30 receives the vehicle travel distance information from the travel distance signal generator 32, and performs known geometric processing on the input digital signal every fixed travel to obtain rut information. Note that the signal processing device 30 controls the signal switch 26 and the A/D converter 28 via a line 34.

The road rut information obtained in this way is stored in a storage device (magnetic tape, magnetic disk, etc.) 36.

[effect] As mentioned above, according to the method according to the invention.

Since information on road ruts can be detected regardless of the presence of natural (sunlight) light, there is a remarkable effect that road ruts can be measured during daytime operations.

[Change in life] In the above embodiment, the road surface is scanned with a laser using an optical scanner, but the invention is not limited to this. For example, a lens (cylindrical or semicircular in cross-section A laser bright line (PO
~PN), and the laser beam is optically modulated at the same frequency as the scanning frequency of the scanner in the embodiment, and a scanner is not required. Furthermore, the placement positions of the scanner 12 and the light receiver 14 may be exchanged. Furthermore, if a plurality of light receivers 14 are provided, highly accurate measurement is possible. Furthermore, if the signal switch 26 is provided after the light receiver 14 and the outputs of the signal switch 26 are taken out sequentially, the number of amplifiers 22 and filters 24 can be reduced to one each. This variation is
The effect increases as the number of semiconductor light spot position detection elements increases.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the device according to the present invention, and FIG.
It is a drawing which shows the detail of the component of the attachment of a figure. In the figure, 10 is a laser generator, 12 is an optical scanner, R is a road surface, 14 is a light receiver, 8 is an optical filter, 20 is a semiconductor light spot position detector, and 24 (1) to 24 (N) are electric filters. shows.

Claims (4)

[Claims] (1) Regarding the method of measuring road surface cross-sectional shapes such as road surface ruts by emitting laser light from a traveling vehicle, (a) Laser light illuminates the road surface at regular intervals approximately perpendicular to the direction of travel of the vehicle. (b) Receive the laser beam reflected from the road surface with a receiver mounted on the vehicle; (d) Pass the laser beam received by the receiver through an optical filter whose center frequency is the same as the frequency of the laser beam. (e) The outputs of the plurality of semiconductor light spot position detection elements are converted into electrical signals by a plurality of semiconductor light spot position detection elements, each of which has a center frequency equal to the frequency corresponding to the constant period. and (f) sequentially extracting the outputs of the plurality of electric filters to obtain information on the cross-sectional shape of the road such as road ruts. (2) The method according to claim (1), wherein in (f) above, information on the cross-sectional shape of the road surface is obtained based on information on scanning the road surface by laser light and information on the distance traveled by the vehicle. (3) Regarding the method of measuring road surface cross-sectional shapes such as road surface ruts by emitting laser light from a traveling vehicle, (a) Laser light illuminates the road surface at regular intervals approximately perpendicular to the direction of travel of the vehicle. (b) Receive the laser beam reflected from the road surface with a receiver mounted on the vehicle; (d) Pass the laser beam received by the receiver through an optical filter whose center frequency is the same as the frequency of the laser beam. (e) sequentially extracting the outputs of the plurality of semiconductor light spot position detecting elements; (f) the conductor sequentially extracted in (e) above; The output of the light spot position detection element is input to an electric filter whose center frequency is equal to the frequency corresponding to the above-mentioned fixed period, and (f) the output of the above-mentioned electric filter is used to obtain information on road surface cross-sectional shapes such as road surface ruts. A method for measuring a cross-sectional shape of a road surface. (4) The method according to claim (3), in which, in the above (f), information on the cross-sectional shape of the road surface is obtained based on information on scanning the road surface by laser light and information on the distance traveled by the vehicle.