JP3357935B2 - Distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device,
In particular, the present invention relates to a distance measuring device that performs leveling, distance measurement, and the like using a laser beam that is rotationally projected.

[0002]

2. Description of the Related Art As a conventional distance measuring device of this type, there is a level sensor shown in FIG.
No.).

FIG. 7 is a block diagram of a level sensor.
This level sensor includes wedge-shaped light receiving elements 71A and 71B for receiving a laser beam LB rotationally projected from a laser beam projector (not shown), and a height position detection circuit 72 including an amplifier circuit, a peak hold circuit, a comparison circuit, and the like. When,
Waveform shaping that is arranged so as to sandwich the wedge-shaped light receiving elements 71A and 71B and that receives the laser beam LB rotationally projected from the laser beam projecting device, and that shapes the signals from the light receiving elements 71C and 71D. Circuits 73A and 73B, a time detecting circuit 74 for detecting the time from when the laser beam LB outputs the light receiving element 71C to when the laser beam LB outputs the light receiving element 71D based on signals from the waveform shaping circuits 73A and 73B, and a time detecting circuit CPU 75 that calculates the distance from the laser beam projector to the sensor body and the height position of laser beam LB based on the time information from 74 and the height position information from height position detection circuit 72.
And a display 76 for displaying the calculation result of the CPU 75.

The operation of this level sensor will be described with reference to the flowchart of FIG.

First, the analog outputs of the wedge-shaped light receiving elements 71A and 71B are compared (step S1). Next, when there is an output difference, an arrow is displayed on the display 76 (step S2). This arrow indicates that the sensor body is
B is an instruction to move up or down. Then, the sensor body is moved up and down as indicated by the arrow to determine whether or not the difference between the analog outputs of the wedge-shaped light receiving elements 71A and 71B has disappeared (step S3). When the output difference has disappeared, the center of the laser beam LB is determined. Is displayed as a bar in the sense that is detected (step S4). At this time, a marking operation is performed.

The time detecting circuit 74 includes a light receiving element 71
Based on the time information t detected by the time detection circuit 74, the CPU 75 calculates the distance R to the laser projector by the following equation based on the time during which the laser beam LB scans the interval L between C and 71D ( Step S5).

R = TL / 2πt Equation (1) Equation (1) indicates the time T required for the laser beam LB to make one rotation and the time t required to cross between the light receiving elements 71C and 71D.
And an arbitrary radial distance from the center of beam rotation of the laser beam projector and an interval L between the light receiving elements 71C and 71D have a relationship of t / T = L / 2πR.
In the expression (1). The distance R thus obtained is held at the minimum value and is digitally displayed on the display 76 (step S6). As a result, the distance R
Can be easily read.

[0008]

However, the apparent distance between the light receiving elements 71C and 71D as viewed from the laser beam projector changes due to the inclination of the level sensor, so that the distance R cannot be determined accurately. To find the distance R accurately,
There is a problem that the level sensor for the laser beam projector must be tilted in the left-right direction, and the measurement operation is complicated.

Further, when there is uneven rotation of the laser beam LB, the time t at which the laser beam LB crosses the light receiving elements 71C and 71D is not constant, and as a result, the distance from the laser beam projector to the level sensor cannot be measured accurately. Therefore, conventionally, the motor for rotating the laser beam LB is controlled to eliminate the rotation unevenness. However, since the rotation unevenness cannot be sufficiently eliminated, there is a problem that the distance measurement cannot be accurately performed. .

The present invention has been made in view of such circumstances, and an object thereof is to provide a distance measuring device capable of accurately and easily measuring the distance from a laser beam projector to a level sensor. is there.

[0011]

In order to solve the above-mentioned problems, a distance measuring apparatus according to the present invention is provided in a measuring apparatus main body, and rotationally projects a laser beam to form a plane of light. Means for reflecting the laser beam, the means being disposed away from the measuring device main body, having at least three marks, forming a triangle with the three marks on a plane of the light, and reflecting the laser beam; A light receiving unit provided in the measuring device main body and receiving the reflected light from the reflecting unit to generate an output corresponding to the three marks; and the light receiving unit provided in the measuring device main body and detected by the light receiving unit. Time measuring means for measuring a time interval between outputs corresponding to the three marks, and a distance provided in the measuring device main body and for calculating a distance to the reflecting means based on the time interval measured by the time measuring means. Calculation means, rotation angle detection means provided in the measurement device main body, for obtaining a rotation angle of the triangle in the plane of the light based on a comparison of a plurality of time intervals measured by the time measurement means, and the measurement A distance correction unit provided in the apparatus main body and configured to correct the distance calculated by the distance calculation unit based on the rotation angle obtained by the rotation angle detection unit.

Further, in the distance measuring apparatus according to the present invention, the measuring apparatus main body may include a rotation unevenness correcting means for correcting rotation unevenness of the laser beam, and a correction value obtained by the rotation unevenness correcting means. Second distance correcting means for correcting the distance.

Further, in the distance measuring apparatus according to the present invention, the rotation unevenness correcting means may include: a rotary encoder;
A pulse interval time detecting means for detecting a pulse interval time of the rotary encoder.

[0014]

In the distance measuring apparatus according to the first aspect of the present invention, the time interval of the output corresponding to the three marks of the reflection means detected by the light receiving means is measured, and the distance to the reflection means is measured based on the measured time interval. The distance is calculated by the distance calculating means, and based on the comparison of the plurality of measured time intervals, the three
Since the rotation angle of the triangle formed by the number of marks is obtained and the distance calculated by the distance calculation means is corrected based on the obtained rotation angle, the reflection means is inclined to project the laser beam. Even if the apparent interval between the three marks as viewed from the apparatus main body changes, the distance to the reflecting means can be accurately obtained without adjusting the inclination of the reflecting means.

In the distance measuring apparatus according to the second aspect of the present invention, the rotation unevenness of the laser beam is corrected by the rotation unevenness correction means, and the distance calculated by the distance calculation means based on the correction value by the rotation unevenness correction means. Is corrected, so that the distance to the reflecting means can be measured more accurately.

Further, in the distance measuring apparatus according to the third aspect of the present invention, the rotational unevenness correcting means is constituted by a rotary encoder and a pulse interval time detecting means for detecting a pulse interval time of the rotary encoder. Since the distance calculated by the distance calculation means is corrected based on the correction value by the correction means, the distance to the reflection means can be measured more accurately.

[0017]

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

FIG. 1 is a longitudinal sectional view showing a laser beam projecting device of a distance measuring device according to one embodiment of the present invention, and FIG. 2 is a perspective view showing a reflecting device of the distance measuring device according to one embodiment of the present invention. It is. A distance measuring apparatus according to one embodiment of the present invention includes the laser beam projecting device of FIG. 1 and the reflecting device of FIG.

The laser beam projecting device comprises a projecting device body 1
And a leveling unit 2. A laser diode 4 for emitting a laser beam LB is fixed in a housing 3 of the light emitting device main body 1. Above the laser diode 4, the laser beam L emitted from the laser diode 4
The projection lens 5 for condensing B is disposed while being held by the holder 13. A beam splitter 6 is fixed above the projection lens 5, and a condenser lens 7 is fixed to the left of the beam splitter 6. A light receiving element (light receiving means) 8 is fixed at a focal position of the condenser lens 7. A compensator 23 for compensating the inclination of the light emitting device main body 1 is fixed to the housing 3.

Above the beam splitter 6, a rotary cylinder 9
Is disposed, and the rotary cylinder 9 is supported by the housing 3 via a bearing 10 so as to be rotatable in the horizontal direction. Further, a motor 12 for rotating the rotary cylinder 9 via a transmission belt 11 is provided to the left of the light receiving element 8. A penta-mirror 1 that guides the laser beam LB transmitted through the projection lens 5 and the beam splitter 6 in the horizontal direction in the rotary cylinder 9.
4, 14 are fixed.

The rotary cylinder 9 has an opening 9a through which a horizontal laser beam LB from the pentamirror 14 passes. On the other hand, a large number of openings 3a for emitting the laser beam LB from the opening 9a to the outside are formed over substantially the entire circumference in the housing 3, and the opening 3a has a transparent protective glass. 27 is fixed. When the rotary cylinder 9 is rotated by the motor 12, the laser beam LB transmitted through the protective glass 27 and emitted to the outside is scanned in a 360 ° direction on a horizontal plane.

The pulse disk 1 is provided below the rotary cylinder 9.
3 is fixed, and the detector 20 is sandwiched between the pulse disks 13.
Is arranged. The pulse encoder 13 and the detector 20 constitute a rotary encoder 21.

The leveling unit 2 includes an upper plate 15 fixed to a lower portion of the housing 3 of the light projecting device main body 1 and a lower plate attached to the upper plate 15 via three leveling screws 17. 18 The light emitting device body 1 has a circular bubble tube 3 (not shown).
4 and leveling screw 17 while looking at circular bubble tube 34.
Can be leveled up to ± 20 'by leveling. After leveling with the leveling screw 17, the compensator 2
The automatic tilt correction function 3 works, and the projector 1 automatically obtains horizontal accuracy of ± 10 ″ or less.

As shown in FIG. 2, a reflection device (reflection means)
Reference numeral 30 denotes a resin main body 31 having a step, first and second reflex sheets (marks) 32A and 32B affixed to the flat surface 31a of the main body 31, and a third reflex sheet affixed to the flat surface 31b of the main body 31. (Mark) 32C and a stake 3 planted on the lower surface of the main body 31 for fixing the main body 31 to the ground.
3 and a circular bubble tube 34 provided on the upper surface of the main body 31 for horizontally setting the main body 31 at the measurement point.

As described above, the first and second reflex sheets 3
2A and 32B are located on the plane 31a of the main body 31, and the third
Is located on the flat surface 31b of the main body 31,
The front edge 32a (mark) of the first reflex sheet 32A in the laser beam rotation direction and the front edge 32b (mark) of the second reflex sheet 32B in the laser beam rotation direction.
Are separated by an interval L1, and the front edge 32a (mark) of the first reflex sheet 32A and the front edge 32c (mark) of the second reflex sheet 32C in the laser beam rotation direction.
Are separated by an interval L2. Further, as shown in FIG. 2 or FIG. 3, the three edges 32a, 32a are placed on a horizontal plane of light formed by the rotational projection of the laser beam LB.
A virtual triangle is formed by b and 32c. Edge 32
An angle θ1 is formed by a straight line connecting a and 32b and a straight line connecting edges 32a and 32c.

FIG. 5 is a block diagram of the laser beam projector of FIG.

The laser diode 4, the light receiving element 8, and the rotary encoder 21 are electrically connected to a time detecting circuit (time measuring means) 26, respectively. The time detection circuit 26 is electrically connected to the CPU 25, and the CPU 25 is electrically connected to the display 28.

The laser beam LB rotationally projected from the laser beam projecting device is reflected by the reflection sheet 32A of the reflecting device 30,
The light is reflected by 32B and 32C and returns to the laser beam projector with a time difference. The returned laser beam LB
Is received by the light receiving element 4 and converted into an electric signal (light receiving signal). The time detecting circuit 26 detects times t1 and t2 described later based on the light receiving signal, and outputs time data to the CPU 25. Further, a rotation pulse of the rotary encoder 16 is output in conjunction with the rotation of the laser beam LB, and the time detection circuit 26 detects a pulse interval and inputs data to the CPU 25. The CPU 25 performs an operation described below based on the data, corrects the inclination of the reflection device 30 and the rotation unevenness of the laser beam LB, and obtains an accurate distance. The distance obtained by the calculation is displayed on the display 28.

FIG. 3 is a diagram showing the principle of the present invention. C
The distance calculation executed by the PU 25 will be described with reference to FIG.

The time that the laser beam LB crosses the interval L1 between the edge 32a of the first reflex sheet 32A and the edge 32b of the second reflex sheet 32B is represented by t1 (the output of the light receiving element 8 corresponding to the edge 32a of the first reflex sheet 32A). The time interval between the time point and the output time point of the light receiving element 8 corresponding to the edge 32b of the second reflex sheet 32B) and the interval L2 between the edge 32a of the first reflex sheet 32A and the edge 32c of the third reflex sheet 32C are defined as the laser beam LB. Crosses the time t2 (the output point of the light receiving element 8 corresponding to the edge 32a of the first reflex sheet 32A and the third reflex sheet 32C
(Time interval from the output time point of the light-receiving element 8 corresponding to the edge 32c), and if the laser beam LB is scanning at = T in one rotation time, the distance R from the light projecting device body 1 to the reflecting device 30 is Can be obtained by the following equation, as in the conventional example: R = L1 · T / 2πt1 (1)

However, assuming that the reflecting device 30 is inclined by the angle θ2 as shown in FIG. 3, ΔL1 = L1 (1-Co
An error of sθ2) occurs, and an accurate distance cannot be obtained.

Therefore, the apparent distances L1 'and L2' from the light projecting device body 1 are as follows: L1 '= L1 · Cos θ2 (2) L2' = L2 · Cos (θ1 + θ2) (3)

However, since the lengths of the distances L1 'and L2' cannot be measured in practice, the distances L1 'and L2' are replaced with the time traversed by the laser beam LB. That is, L1 ': L
Since 2 ′ = t1: t2, θ2 is obtained from the relationship, and θ2 = Tan ⁻¹ {(1 / Sinθ1) · (L1 · t2 / L2 · t1) − (Cosθ1 / Sinθ1)} (4) By substituting the equation (4) into the equation (2), an apparent interval L1 ′ corresponding to the inclination of the reflection device 30 can be obtained.

L1 ′ = L1 · Cos ｛Tan ⁻¹ [(1 · Sinθ1) · (L1 · t2 / L2 · t1) − (Cosθ1 / Sinθ1)]｝ (5) Therefore, the correction formula R ′ = L1 '· T / 2πt1 (6) is obtained.

When an actual numerical value is entered, L1 = 100
mm, L2 = 130 mm, θ1 = 9 °, rotation speed of the laser projector = 300 rpm, distance R = 100 m, θ2 = 45 °, t1 = 22.51 μs, t2 = 24.32 μs
If the time is measured with the accuracy of
1 '= 70.722 mm is calculated, and R' = 99.94 m is calculated from the above equation (6). If the same numerical value is calculated by the expression (1) without correction, R = 141.4 m, and an error of about 41 m occurs.

Although the above calculation does not take into account the rotational unevenness of the laser beam LB, t1 and t1 in the equations (5) and (6) are not considered.
By inserting a rotation unevenness correction value at the time t1, more accurate distance measurement can be performed. Hereinafter, this rotation unevenness correction will be described with reference to FIG. FIG. 4 is a timing chart of the rotation unevenness correction.

The time when the laser beam LB crosses L1 is represented by t.
1, the time that the laser beam LB traverses L2 is t2, the time that the laser beam LB makes one rotation is T, the number of pulses of the rotary encoder 21 is N, and the pulse interval time is p1 to pn.
The time interval in the corresponding pulse of the rotary encoder from the start time of t1 is tp1, and the time interval in the corresponding pulse of the rotary encoder from the end time of t1 is tp4, t2.
Assuming that the time interval within the corresponding pulse of the rotary encoder from the end point of tp6 is tp6, the correction time tp1 'for tp1
, P1 and T / N are represented by tp1: tp1 '= P1: T
/ N, and tp1 ′ = tp1 · T / N · P1 (7) is obtained.

Similarly, the relationship between the correction time tp4 'of tp4 and P4, T / N is as follows: tp4: tp4' = P4: T /
N, tp4 '= tp4.T / N.P4 (8) Further, the correction time tp6' of tp6 is obtained by tp6 '= tp6.T / N.P6 (9).

Except for the correction times tp1 ', tp4' and tp6 ', the pulse count number n of the rotary encoder 21 is T
/ N is used, the rotation unevenness correction value t1 ′ at the time t1 is t1 ′ = (tp1 · T / p1 · N) + nT / N + (tp2 · T / pn · N) The rotation unevenness at the time t2 The correction value t2 'is obtained by the following equation (10): t2' = (tp1.T / p1.N) + nT / N + (tp3.T / pn.N). Equation (11) This correction value is obtained by adding t1 = t1 ′ to the equations (5) and (6).
By substituting t2 = t2 ', an accurate distance calculation is finally performed.

As described above, if the uneven rotation of the laser beam LB is considered, the distance to the reflection device 30 can be measured more accurately.

FIG. 6 is a perspective view showing a reflecting device of a distance measuring device according to a modification of the present invention. Portions common to the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted. In the above-described embodiment, three reflex sheets 32A, 32 of the same size are used.
B and 32C have been described, but as a modification, as shown in FIG. You may make it stick on each of the flat surfaces 31b.

The front edge 52 of the large reflex sheet 52
a and the rear edge 52b correspond to the distance L1 (FIG. 2), and correspond to the front edge 5 of the large reflex sheet 52.
An interval L12 between the front edge 53a of the small reflex sheet 3a and the front edge 53a of the small reflex sheet 53 corresponds to an interval L2 (FIG. 2), and the edges 52a, 52b of the reflex sheet 52 and the reflex sheet 52 53
A virtual triangle is formed with the edge 53c of the left sheet, and a straight line connecting the edge 52a and the edge 52b of the reflex sheet 52;
An angle θ11 is formed by a straight line connecting the edge 52a of the reflex sheet 52 and the edge 53c of the reflex sheet 53, and the angle θ11 corresponds to the angle θ1 (FIG. 2).

According to the distance measuring apparatus of this modified example, the same effect as in the above-described embodiment can be obtained.

In the above-described embodiments and modified examples, the case where the edge of the reflex sheet is used as the mark has been described. However, the mark here is a broad concept including the edge of the reflex sheet. However, the present invention is not limited to this, and various other marks can be used.

[0045]

As described above, according to the distance measuring device of the first aspect of the present invention, the apparent distance between the three marks as viewed from the measuring device main body that projects the laser beam with the reflecting means inclined. Even if has changed, the distance to the reflecting means can be accurately obtained without adjusting the inclination of the reflecting means,
Measurement work becomes easy.

According to the distance measuring device of the present invention, the distance to the reflecting means can be measured more accurately.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a laser beam projecting device of a distance measuring device according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a reflecting device of the distance measuring device according to one embodiment of the present invention.

FIG. 3 is a diagram showing the principle of the present invention.

FIG. 4 is a timing chart of rotation unevenness correction.

FIG. 5 is a block diagram of the laser beam projector of FIG. 1;

FIG. 6 is a perspective view showing a reflecting device of a distance measuring device according to a modification of the present invention.

FIG. 7 is a perspective view of a level sensor.

FIG. 8 is a flowchart for explaining the operation of the level sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projector main body 4 Laser diode 8 Light receiving element 9 Rotating cylinder 11 Transmission belt 12 Motor 13 Pulse disk 14 Penta mirror 20 Detector 21 Rotary encoder 25 CPU 26 Time detection circuit 30 Reflector 32A First reflex sheet 32B Second Reflex seat 32C Third reflex seat 32a, 32b, 32c Edge

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01C 3/06 G01C 15/00

Claims (3)

(57) [Claims] 1. A light emitting means provided on a measuring device main body, for projecting a laser beam by rotation to form a plane of light, and provided at least three marks apart from the measuring device main body, A reflecting means for forming a triangle on the plane of light with the three marks and reflecting the laser beam; and a reflecting means provided on the measuring device main body for receiving reflected light from the reflecting means and forming the three marks Light-receiving means for generating an output corresponding to the following; time-measuring means provided in the measuring device main body for measuring a time interval between outputs corresponding to the three marks detected by the light-receiving device; A distance calculating means for calculating a distance to the reflecting means based on a time interval measured by the time measuring means; and a plurality of distance measuring means provided in the measuring device body and measured by the time measuring means. Rotation angle detection means for obtaining a rotation angle of the triangle in the plane of the light based on a comparison of time intervals; and the distance calculation provided on the measurement device main body and based on the rotation angle obtained by the rotation angle detection means. A distance correcting means for correcting the distance calculated by the means. 2. The apparatus according to claim 1, wherein the measuring apparatus main body includes: a rotation unevenness correction unit configured to correct rotation unevenness of the laser beam; and a second distance correction unit configured to correct the distance based on a correction value obtained by the rotation unevenness correction unit. The distance measuring device according to claim 1, wherein the distance measuring device is provided. 3. The distance measuring apparatus according to claim 2, wherein said rotational unevenness correcting means includes a rotary encoder and a pulse interval time detecting means for detecting a pulse interval time of said rotary encoder.