JPH09287932A - Laser displacement meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the laser displacement meter, which can widen the measuring range wherein the measurement can be performed in the vertical direction, and can perform the precise measurement by increasing the parts where the measurement of the irregularities in the cross-sectional direction can be performed. SOLUTION: This laser displacement meter projects plurality of slit beams obliquely onto a lane to be measured, respectively. At the same time, the slit beams are measured by line sensor cameras 3 from the upper side of the plane to be measured, and the irregularities of the plane to be measured are obtained by the principle of triangulation. In this case, a plurality of the slit beams are monochromatic beams having mutually different wavelengths. Furthermore, as the line sensor cameras 3, a plurality of the cameras, which can separately measure the monochromatic beams having the different wavelengths, are used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laser displacement meter. For example, it is applied to road surface shape measurement and the like.

[0002]

2. Description of the Related Art An example of a conventional road surface shape measuring vehicle is shown in FIG. One of the functions of the road surface shape measuring vehicle 1 is to measure "rut" of the road surface, which is one of the objects of road surface evaluation, that is, the unevenness in the transverse direction by the multipoint non-contact measurement method. That is, a large number of slit projectors 2 are attached to the front bumper of the road shape measuring vehicle 1, and two line sensor cameras 3 are attached to the front of the passenger compartment. The slit light projector 2 irradiates the slit light, which is a laser light, obliquely with respect to the road surface, and the number of slit light is 5
Four of them have a width of 1 to 2 mm.

The line sensor camera 3 observes slit light formed on the road surface, and two line sensor cameras 3 are provided for the purpose of enlarging the measurable lateral width. Therefore, theoretically, one line sensor camera 3 can be used. As the line sensor camera 3, a CCD (solid-state image sensor) camera arranged in one dimension is generally used. As the unevenness in the transverse direction of the road surface, the slit light coordinates (X _s , Y _s ) are calculated according to the following equations (1) and (2) based on the principle of triangulation.

[0004]

[Equation 1]

However, as shown in FIG. 3, (X _c , Y _c ) is the lens center coordinate of the line sensor camera 3, and (X _l , Y _l )
Are coordinates of the projection center of the slit projector 2. The origin is the reference road surface at the center of the vehicle (1100 mm from the slit projector 2).
Flat road surface assumed below) The coordinate axes are + X on the passenger side and + Y on the vertical side. Further, θ _m is the observation angle of the observation line of the line sensor camera 3, and θ _l is the projection angle of the projection light of the slit projector 2. The angle is 0 ° vertically downward and positive is counterclockwise. The observation angle θ _m is calculated by the following equation (3).

[0006]

[Equation 2]

However, as shown in FIG. 4B, l _c is the mapping position of the line sensor camera 3, and H _c is the distance between the line sensor camera 3 and its lens 4. Mapping position l
_c is calculated by the following equation (4).

[0008]

(Equation 3)

However, as shown in FIG. 4A, N _p is the total number of pixels of the line sensor camera 3, L _c is the length of the line sensor camera 3, and the pixel address at the mapping position l _c .

[0010]

In the above-mentioned conventional road surface shape measuring vehicle, the lens center coordinates (X _c , Y _c ) of the line sensor camera 3 and the projection angle θ _l of the projected light of the slit projector 2 are fixed. Therefore, if the observation angle θ _m of the observation line of the line sensor camera 3 is measured, based on the principle of triangulation, the slit light coordinate (X
_s , Y _s ) is required for the transverse unevenness.

Here, as shown in FIGS. 11 (a) and 11 (b), the measurement range that can be measured in the vertical direction as the unevenness in the transverse direction depends on the interval at which the slit projector 2 is arranged.
Be restricted. That is, the shorter the interval at which the slit projector 2 is arranged, the shorter the interval at which the road surface is obliquely irradiated, and therefore the measurement range that can be measured in the vertical direction tends to become narrower.

On the other hand, if the interval at which the slit projectors 2 are arranged is increased in order to widen the measurement range that can be measured in the vertical direction, the measurement pitch in the horizontal direction becomes rough,
The number of measurable points of the unevenness in the transverse direction is reduced. In other words, if the measurement range that can be measured in the vertical direction is widened, the number of points that can measure unevenness in the transverse direction will decrease, and precise measurement will not be possible. If you try
There is a possibility that the measurement range that can be measured in the vertical direction becomes narrow and measurement becomes impossible. The present invention has been made in view of the above-mentioned prior art, and it is possible to widen the measurement range that can be measured in the vertical direction, and increase the number of locations where the unevenness in the transverse direction can be measured, thereby enabling precise measurement. An object is to provide a laser displacement meter.

[0013]

According to the present invention for achieving such an object, a plurality of slit lights are radiated obliquely to a surface to be measured, and a line sensor camera is used to detect the slit light from above the surface to be measured. In the laser displacement meter which measures the slit light and obtains the irregularities of the surface to be measured by the principle of triangulation, the plurality of slit lights are monochromatic light of different wavelengths alternately, and as the line sensor camera, It is characterized in that a plurality of monochromatic lights having different wavelengths can be separated and measured. Here, the line sensor camera is equipped with an optical filter for separating light of each wavelength.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, two kinds of slit projectors 2 ', 2 "capable of irradiating monochromatic light of different wavelengths are alternately arranged, and the slit side projector 2', 2 ' While irradiating the light of the wavelength obliquely as indicated by the middle broken line and the solid line, the slit light on the measured surface is projected from above the measured surface by the two line sensor cameras 3 ′ and 3 ″ equipped with the optical filter 5. measure. The optical filter 5 is for separating and measuring monochromatic light of different wavelengths emitted from the two types of slit projectors 2'and 2 ".

Therefore, by the line sensor camera 3 ',
If the monochromatic light slit shown by the solid line in the figure is observed, the slit projector 2'is the only slit projector that projects the slit light with respect to the line sensor camera 3 ', and the slit projector 2 "is irrelevant. On the contrary, if the line sensor camera 3 ″ observes a slit of monochromatic light shown by a broken line in the figure, the slit projector 2 ″ is the only slit projector that projects the slit light in the line sensor camera 3 ″. , The slit projector 2'is irrelevant.

That is, according to the present invention, since slit lights having different wavelengths are alternately irradiated and each wavelength is separately measured by the line sensor cameras 3'and 3 ", the wavelengths can be measured vertically. Since the measurement range can be widened and the lateral unevenness measured for each wavelength can be combined, as a result, the number of locations where the lateral unevenness can be measured can be increased and precise measurement can be performed. It is possible to provide a laser displacement meter.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. 5 to 9 show a laser displacement meter according to an embodiment of the present invention. The present embodiment is applied to the road surface shape measuring vehicle 1 shown in FIG. As shown in the figure, at a height of 1100 mm from the reference road surface, a large number of slit projectors 2 are attached so as to be inclined with respect to the reference road surface.

The slit projectors 2 are arranged alternately with those for irradiating visible light indicated by solid lines in the figure and those for irradiating infrared light indicated by broken lines in the figure. As shown in FIGS. 7 and 8, there are 44 slit projectors with an inclination angle of 45 ° with respect to the road surface and 10 with an inclination angle of 55.5 ° with respect to the road surface. Are arranged in two rows in the central part and three rows in the outer part.

Further, two line sensor cameras 3 are provided at two locations at a height of 2588 mm from the reference road surface. That is, in this embodiment, a total of four line sensor cameras 3 are arranged. A filter for visible light and a filter for infrared light are attached to the line sensor camera 3 at each location.

Accordingly, the line sensor camera 3 to which the filters having different selected wavelengths are attached is the slit projector 2
Either infrared light or visible light of the slit light emitted from the device is separated and selectively observed. Therefore,
If only the slit light of infrared light is observed by one of the line sensor cameras 3, then there will be every other slit light of one of the line sensor cameras 3, and similarly, the other line sensor. If only the slit light of the visible light is observed by the camera 3, the slit light exists in every other line sensor camera 3 as well.

That is, considering the intervals at which the slit light projectors 2 are arranged for the slit light beams of different wavelengths, the intervals at which the slit light projectors 2 are arranged are effectively long, and the vertical measurement range is wide. Become. Moreover, in practice, the interval at which the slit light projector 2 is arranged does not become long unless the type of wavelength is taken into consideration, so the number of locations where the unevenness in the transverse direction can be measured is reduced. It doesn't.

As described above, in this embodiment, two kinds of slit projectors 2 capable of irradiating only infrared light or visible light are alternately arranged, and different monochromatic light is obliquely applied to the road surface. On the other hand, by measuring the slit light on the road surface separately from above the road surface by the two line sensor cameras 3 equipped with optical filters, it is possible to maintain a high lateral pitch. There is an advantage that the measurement range in the vertical direction can be expanded.

As shown in FIG. 9, a lens 4 is attached to the front surface of each line sensor camera 3, and the lens 4 is generally accompanied by optical distortion. Therefore, FIG.
As shown in 0, the observation angle θ _m of the line sensor camera 3 is deviated by the optical distortion of the lens 4 and observed as θ _m ′, the mapping position l _c of the line sensor camera is also deviated, and the mapping position l _c is changed. The pixel address N shown also causes an error ΔN from the theoretical value N _t to the actual measurement value N _m as in the following equation (5).

ΔN = N _t −N _m (5) Therefore, in the present embodiment, as shown in FIG. 6, pixel address correction is performed for _four line sensor cameras 3 ₁ , 3 ₂ , 3 ₃ , 3 _4. The value ΔN was obtained in advance. By correcting this pixel address correction value ΔN at the 0 level as shown in FIG. 6, it is possible to remove the optical distortion of the lens 4. Further, as shown in FIG. 6, the pixel address correction value is not uniform in the central portion and the peripheral portion and changes according to the pixel address, and the value is different for each line sensor camera 3. It turns out that The length of one pixel is 0.64 mm.

Therefore, as shown in FIG. 12, this pixel address correction value ΔN is stored in advance as a correction table 5 for each line sensor camera 3 ₀ , 3 ₁ , 3 ₂ , 3 ₃ and corresponds to each pixel position N. By adding the corrected value ΔN to the measured value N _m to obtain the theoretical value N _t (= ΔN + N _m ), and substituting the theoretical value N _t as the pixel address N in the equation (4),
An accurate tan θ _m can be obtained by removing the optical distortion of the lens. By substituting the tan θ _m obtained in this way into the above equations (1) and (2), it is possible to remove the optical distortion of the lens and obtain an accurate slit light coordinate (X _s , Y _s ). it can.

As described above, in the present embodiment, four correction tables 5 for the optical lens are prepared for each of the four line sensor cameras 3 ₀ , 3 ₁ , 3 ₂ , 3 ₃ , but for each line sensor camera 3 When the optical distortions of 1 are almost the same, it is also possible to approximately share one correction table 5. Incidentally, such a correction table 5 is not always necessary. For example, each line sensor camera 3 ₀ , 3 ₁ ,
As the optical lenses 3 ₂ and 3 ₃ , a plurality of lenses may be combined to cancel the optical distortion, or an optical lens whose optical distortion is so small that it can be ignored may be selected.

[0027]

As described above in detail with reference to the embodiments, in the present invention, slit light beams having different wavelengths are alternately irradiated, and each wavelength is separated by a line sensor camera and independently. Since it is possible to measure, it is possible to widen the measurement range that can be measured in the vertical direction, and since it is possible to combine the unevenness in the horizontal direction that is measured for each wavelength, as a result, the location where the unevenness in the transverse direction can be measured It is possible to provide a laser displacement meter capable of performing accurate measurement by increasing the number of laser beams.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a laser displacement meter of the present invention.

FIG. 2 is a perspective view of a road surface shape measuring vehicle.

FIG. 3 is an explanatory diagram showing the principle of measurement of rutting by the triangulation method.

FIG. 4 is a structural diagram of a line sensor camera.

FIG. 5 is an explanatory diagram showing a layout of a slit projector and a line sensor camera.

FIG. 6 is a graph showing a pixel address correction value.

FIG. 7 is an explanatory diagram showing an array of slit projectors.

FIG. 8 is an explanatory diagram showing a slit projector.

FIG. 9 is an explanatory diagram showing a line sensor camera.

FIG. 10 is an explanatory diagram showing an influence of optical distortion of a lens.

FIG. 11 is an explanatory diagram showing the relationship between the arrangement of the slit projector and the measurement range.

FIG. 12 is an explanatory diagram showing a correction table.

[Explanation of symbols]

 1 Road surface shape measurement vehicle 2, 2 ', 2 "Slit projector 3, 3', 3" Line sensor camera 4 Lens 5 Optical filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kaoru Onuki Kaoru Onuki 3rd 3rd Yushima, Bunkyo-ku, Tokyo Within Tokyo Road Engineer Co., Ltd. (72) Yoshimichi Ono 3rd 1st 3rd Yushima, Bunkyo-ku, Tokyo Tokyo Road Engineer Co., Ltd. (72) Inventor Shinnori Koda No.3 Yushima 3-chome, Bunkyo-ku, Tokyo Tokyo Road Engineer Co., Ltd.

Claims (2)

[Claims] 1. A plurality of slit lights are obliquely applied to a surface to be measured, and the slit light is measured from above the surface to be measured by a line sensor camera,
In the laser displacement meter for obtaining the unevenness of the measured surface by the principle of triangulation, the plurality of slit lights are monochromatic light of different wavelengths alternately, and as the line sensor camera, monochromatic light of different wavelengths. A laser displacement meter characterized by using a plurality of things that can be measured separately. 2. The laser displacement meter according to claim 1, wherein the line sensor camera is equipped with an optical filter for separating light of each wavelength.