JPS6285813A - Distance measuring instrument - Google Patents

Abstract

PURPOSE:To measure the distance from a reference line to an object of measurement with high precision by converging light which is irradiated at right angles to the reference line and reflected by the object of measurement by a lens whose optical axis is slanted by a specific angle to the reference line. CONSTITUTION:This instrument consists of the reference line 1, a light emitting element 2, a reflecting mirror 3 which is placed at one end of the reference line 1, the lens 4 arranged at the other end of the reference line 1, a CCD element 5, and a signal processing circuit 6. The reference line 1 is the reference for distance measurement. Then, the reflecting mirror 3 reflects light 11 at right angles to the reference line 1 and this light 11 forms a bright point 10 on the wall surface 12 of a tunnel. Then, the lens 4 installed at a constant angle to the reference line 1 converges the light from the bright point 10 to form an image of the bright point 10 on the element 5. The output signal of the element 5 is processed by the circuit 6 to calculate the position of the center of gravity of the image. Then, this position of the center of gravity is used to determine which direction of the optical axis of the lens 4 the bright point 10 is in. The distance between the reference line 1 and wall surface 12, i.e. height of the wall surface is calculated from the direction, the length of the reference line 1, and the tilt angle theta of the optical axis of the lens 4 to the reference line 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance measuring device, and more particularly, to a distance measuring device used for measuring the cross-sectional shape of a tunnel or the like in V#.

[Conventional technology]

Conventionally, a distance measuring device for measuring the cross-sectional shape of a tunnel of this kind has been used, as shown in Figure 2, to draw a reference line 1 made of a frame or the like having a certain length.
At the moment when the IC bright spot 10 directly above the photodetector 9 placed on the other end VC comes, the signal processing circuit 6 reads the rotation angle of the reflecting mirror 7 using a device such as a rotary encoder 8 that detects the rotation angle, and H= According to the formula LXtanθ, the length L of reference line 1
The distance H between the reference line 1 and the tunnel wall 12 is calculated from the original reflection direction 〇 calculated from the rotation angle of the reflecting mirror 7.

[Problems that the invention is supposed to solve]

In principle, the conventional distance measuring device described above.

Although there is no particular problem, when the distance H to the tunnel wall 12 becomes several times the depth L of the reference line 1, the amount of change in the inclination of the reflecting mirror 7 with respect to a constant change in the distance @H becomes small. Conversely, if a reading error of the angle θ occurs due to the resolution of the rotary encoder 8, the calculated constant distance H will have a large error.

Therefore, in order to suppress the detection error of the distance H to below a certain value, the rotary encoder 8 with high resolution is required. As the resolution increases, the rotary encoder 8 becomes larger and more expensive, and requires careful handling, which poses a major obstacle in practical use.7 The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, and It is an object of the present invention to provide a distance measuring device capable of measuring distance M and distance VC with high accuracy without using an angle detecting device such as the above.

Determined Means for Solving the Problem] The distance measuring device of the present invention includes a light source that passes through one end of a reference line and irradiates the entire direction VC in a direction perpendicular to the reference line, and the other end of the reference line has an IC original axis. A constant lens is provided to form an angle with the base reference line, and the reference lens is tilted with respect to the VC lens so that an image of a bright spot hit by the source of the measurement target VC is formed by the lens on the light receiving surface. A photoelectric element is provided at the other end of the line, and this element 1! The device includes a signal processing circuit that processes signals from the elements to determine the distance between the reference line and the measurement target.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic side view of an embodiment of the present invention. This embodiment 1 includes a reference line 1, a light emitting source 2, and one end v of the reference line 1.
The device consists of a reflecting mirror 3, a lens 4 with the other end Vc of the reference line 1 measured, a CCD element 5, and a signal processing circuit 6. The reference line l serves as a reference for distance measurement. The light 11 coming from the tunnel is bent at right angles to the reference line 1, and the light 11 illuminates the wall surface 12 of the tunnel to form a bright spot 10. Reference line 1iC
On the other hand, the lens 4 installed at a certain angle has the function of condensing the light emitted from the light emitting source 2 that is diffusely reflected by the bright spot 10 per tunnel wall surface 12vc and forming an image of the bright spot 10 on the CCD element 5. The CCD element 5 is imaged by the lens 41C and the t element hits the 9th place and the intensity! '(The signal processing circuit 6 has a function of converting it into a constant electrical signal, and the signal processing circuit 6 forms an image from the lens 4Vc based on the signal 1 from the CCD element 5, determines the center of gravity position of the dimension, and calculates the distance to be measured, that is, up to the tunnel wall surface 11. The function of this device is explained below in order.

The element 11 emitted from the light emitting source 2 is placed at one end of the reference line 1 and is bent by the t-reflector 3 at right angles to the reference line 1vc. This light 11 is diffusely reflected by the tunnel wall surface 121/C and all bright spots 10 are generated. When the image of the bright spot 10 is formed by the lens 4, the lens 4 is set apart from the light 11 in order to identify the height by focusing the image at a different position when the height of the tunnel wall 12 changes. Place it at the other end of the reference line 1 and tilt the original axis with respect to the reference line l so that the bright spot 10 in the required height range can be seen within an appropriate angular range around the entire center of the original axis. are doing. If the height of the tunnel wall 12 is different, the angle at which the bright spot 10 is viewed from the lens 4 will be different, and the imaging position of the bright spot 10 will be different accordingly.
When the CCCD element 5 is completely closed, the entire height of the tunnel wall 12 can be calculated from the imaging position detected by the CCD element 51C.

However, if the height of the tunnel wall 12 is different, the distance between the lens 4 and the bright spot 10 will be different, and if the CCD element 5 is placed at a constant distance from the lens 4vc, the focus will be blurred. Due to this problem, the position of the image cannot be determined accurately.

The king eye of the present invention is arranged so that the CCD element 5 is tilted at a certain angle with respect to the direction perpendicular to the original axis of the lens 4 ic↓
Even if the distance between the bright spot 10 and the lens 4 changes due to a change in the height of the tunnel wall surface 12, the CCD element 5
The bright spot 10 is located at a point on the surface where the bright spot 10 is always in focus.

An example of calculation regarding focusing on the surface of the CCD element 50 in the embodiment shown in FIG. 1 will be shown below.

This calculation example is a case where the length of the reference line 1 is 1 m and the height of the tunnel wall surface is measured within the range of 2 cm to 55 cm.

jan (2/1) = 63.435°, tan
(5, 5/1) = 79.695° Lens original III θ; 69° fCIi, bright spot 10 and lens 4 when the height of T from the tunnel wall is 21
The angle αl between the straight line connecting t and reference line 1 is α1=63
．． 435-69=-5,565', that is, the brightness of 10 appears in the direction of -5,565° with respect to the optical axis of the lens 4.

At that time, the distance 6'AL t between lens 4 and bright spot 10 is 11 Y
s (5,565°) = 2.2256 ■ Focal length F = 50
When an image is formed with a lens of mg, the image position b1 is 0.0195 out of 1/bt=1150-1/2225.6 from the lens formula.
5. b1 = 51.1491 tan On the other hand, bright spot lO when the height to the tunnel wall is 5.5 inches
The angle α2 between the straight line connecting all the lenses 4 and the reference line 1 is.

α2 = 79.695-69 = 10.695° Distance l# between lens 4 and bright spot 10 at that time! ! t2 is 12
= k = 7”3〒25 = 5.5902 m Lens 4 division in the original axis direction 12*coslα21=5.5902XCO5 (10,
695°) = 5.4931m When the image is formed using a lens with a hot spot distance F = 50wm, 1/
b2=1150-115493.1 =0.01982
．． bz -50,4593■ In the case where the height of the tunnel wall surface is 2m and in the case of 55cm, the image position is 1fltlC51,1491-50,4593=0.
There is a difference of 6898m. In other words, if you focus on either one, the other will be out of focus by about 0.7 mm. (
Even if you focus on the center, each will be blurred by about 0.35 m), and this amount can be ignored when trying to find the center position m- of the imaging point and detect the height to the tunnel wall 12. It is conceivable to use the vCCCD element 5 at an angle in order to fully correct the cono-tip blur, which is an amount that cannot be obtained. What will happen will be explained using Figure 3.

Figure 3 shows lens 4 and CCD 5 to aid understanding.
The parts showing the positional relationship are enlarged. lens 4
From vc, if the image of point A is at position A', the image of point B is at position B', and the image of point 0 on the original axis of the lens is 1/C, i at position IC, then A', If the positions of B' and C' match the surface of the COD element, no blurring will occur.

Fi<M'x using mtKrc of the above-mentioned out-of-focus
When used, (JA”=bt=51.1491m OB”=b:,
+=50.4593a+A'A'=OA' Xta
rlcllll=51.491 X tan(5,555
°)=4.9837sam B'B'=OB' Xtanl(Ezl=50.4
593 ?
This is the intersection of the perpendicular to the optical axis of the lens 4 passing through and this original axis.

Further, the angle between the straight line A'B' and a plane perpendicular to the original axis of the lens 4 is as follows.

tan-1((OA"-(JB")/(A'A"+
B'I=1>)=tan-1((51・149]-
50,4593)/, 983□+9.5298))=
tan Q O, 6898/ 14.5135 ) =
tan-' (0,04753) = 2.7210 In other words, when the CCD element 5 is tilted Z7210 with respect to the lens 4vc in the t state, the images of the CCD element 5 and points A and B can be made to coincide at points A' and B'. .

If the intersection of the original axes of the CCD element 5 and the lens 4 is C", then OC"==OA'-A'A' X tan(2,7
21 = 51.1491-4.9837 X tan (
2,721°)=51.1491-0.2369=50
．． 9122 10,000=Vit"+ (1:ΣW IF"=2.
79041=2790.4 pallets 110C'=1150
-1/2790.4=0.0196420C'=50.
9123 That is, the difference between the position C# where the original axis of the lens 4 and the CCD 5 intersect and the image position C' of the bright spot C in the original axis direction is 50.9122-50.9123=-0,0001=
The value -0.1μ is completely negligible when it comes to blurring the focus. By tilting the CCD element 5 in this manner, it is possible to accurately focus the image of the bright spot 10 on the t-C0D element S with respect to the striations of the tunnel wall surface 12 within a required range.

A signal corresponding to the image of the bright spot 1o is sent to the CCL element 5, and this signal is processed by the signal processing circuit 6 to calculate the position of the center of gravity of the image. From this position of the center of gravity, it can be determined in which direction the bright spot 10 is located with respect to the optical axis of the lens 4. From this direction, the length of the reference line 1, and the angle of inclination of the original axis of the lens 4 with respect to the reference line 1vc, the distance between the reference line 1 and the tunnel wall surface 12, that is, the height of the tunnel wall surface can be calculated.

The calculation method is as follows.

1) The position of the center of gravity of @ and the angle of the bright spot 10 with respect to the original axis of the lens 4 are calibrated in advance. The angle α shown in Figure 1 is calculated from the center of gravity position.

2) When the length of the reference line 1 is ftL and the angle of inclination of the lens 40 element axis is θ, the height H to the tunnel wall surface is H=LXtan(θ+α), that is, if α is determined, H is calculated.

In the present invention, the light emitting source 2 may emit light directly in a direction perpendicular to the source 11t-reference line l without using the reflecting mirror 3 shown in FIG. ] A charging element such as a phototransistor array may be used.

〔Effect of the invention〕

As explained above, the present invention uses nine lenses to tilt the source reference line and the source axis at a constant angle from the luminous point when the source irradiated in the direction perpendicular to the reference line hits the measurement target. The constant angle tilt with respect to the direction perpendicular to the original axis is 9 ftl! A high-resolution rotary encoder is created by forming an image on the surface of the element, calculating the center of gravity position using a signal processing circuit, and then calculating the height from the reference line to the measurement target based on the tIL. This method has the effect that the distance from the reference line to the pipe to be measured can be measured with high accuracy without using.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of an embodiment of the present invention, FIG. 2 is a schematic side view of a conventional distance foot device, and FIG. 3 is a portion of the lens 4 shown in FIG. 1. This is an enlarged view of the light path. 1...Reference line, 2...Light source, 3...
...Reflector, 4...Lens, 5.Old...C
CD element, 6... Signal processing circuit, 7...
・Rotating reflector, 8...Rotary encoder, 9
...Original detection part, 10 ... Bright spot, 11.
...Light, 12...Tunnel wall. ／・2′2゛−゛

Claims (1)

[Claims] a light source that passes through one end of a reference line and irradiates light in a direction perpendicular to the reference line; a lens provided at the other end of the reference line so that its optical axis makes a predetermined angle with respect to the reference line; a photoelectric element tilted with respect to the lens and provided at the other end of the reference line so that an image of a bright spot where the light hits the measurement object by the lens is formed on a light-receiving surface; A distance measuring device comprising: a signal processing circuit that processes a signal to determine the distance between the reference line and the measurement target.