JPS63222213A - Distance measuring method, range finder and distance measuring scale - Google Patents

Abstract

PURPOSE:To measure a distance with relatively high accuracy by a simple apparatus, by calculating the distance up to a target from the length of the image of the target having a known length calculated by picking up the image of the target by a telescope, the actual length of the target and the magnifying power of the telescope. CONSTITUTION:For example, a scale 8 having a known length is set to 1m and a mark equally dividing said length into 10 is applied to the scale 8 to form 10 blocks 11. This scale 8 is vertically provided at a distance measuring point to be observed through the objective lens system 2, square lens system 3 and eyepiece system 4 of a telescope 1. The image split by the splitter 4b of the eyepiece system 4 is magnified by a magnifier 5 to be formed into an image on an image sensor 6. The mark 9 of the scale 8 formed into the image on the image sensor 6 and the number of the blocks 11 are calculated and the magnifying power of the telescope is used to calculate the distance up to the distance measuring point by an operation circuit to display the same. By this method, a distance is measured with relatively high accuracy by a simple optical system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance measuring method, a distance meter, and a distance measuring leveling rod.

[Summary of the invention]

The present invention is characterized in that a target of known length is imaged by a telephoto imaging means, and the distance to the target is calculated based on the flaw length on the imaging surface and the telephoto magnification indicated by the image output signal.

[Conventional technology]

In civil engineering surveying, a light wave distance meter (a device that calculates distance based on the phase difference between the intensity-modulated emitted light and the return light from the reflector) is used to optically measure distance. . Stadia measurement II (tachyometry) is also used to calculate distances by reading the intervals between stadia lines marked on the focusing mirror of a leveling instrument or transit telescope using the scale of a telescopic leveling rod.

[Problem that the invention seeks to solve]

Although light wave distance meters have high accuracy, they are expensive and are not suitable for simple surveying using alidades, for example. Furthermore, stadia surveying requires a surveyor to read the scale and calculate distances, which is time-consuming and has the problem of low accuracy.

An object of the present invention is to enable highly accurate digital direct reading and digital display of distance with a simple configuration.

[Means for solving problems]

The distance measuring method of the present invention images a target of known length with a telephoto imaging means, calculates the flaw length on the imaging surface based on the image output signal, and calculates the flaw length on the imaging surface based on the known length, the flaw length, and the objective lens. The distance to the target is calculated and obtained based on the telephoto magnification.

This makes it possible to read the distance as a digital value with a relatively simple configuration.

Further, the distance meter of the present invention has a target of known length (leveling rod 8
), a means for measuring the flaw length of the block row on the imaging surface based on the image output signal, and a means for measuring the number of blocks included in the flaw length on the imaging plane based on the image output signal. and a calculation means for calculating the distance to the target based on the known length, the flaw length, the number of blocks, and the telephoto magnification.

By increasing the number of imaging blocks at long distances and decreasing the number of imaging blocks at short distances, it is possible to perform measurements that effectively utilize the size of the imaging surface.

The distance measurement leveling rod of the present invention includes marks 9 having intervals such that the flaw length can be measured based on the image output signal when an image is captured by the imaging means, and each of the marks has a unit length. A plurality of representative continuous block rows 11
It is characterized in that each block is provided with a barcode-like code pattern that can be distinguished from a pseudo video source.

By decoding the code pattern, length measurement interference can be reduced and the accuracy of measurement values can be increased.

〔Example〕

FIG. 1 shows an optical rangefinder to which the present invention is applied, and FIG. 2 shows a rangefinding leveling rod that is a measurement target.

The rangefinder 1 has an optical system that is generally the same as that of a well-known telescope, and consists of an objective lens system 2, an erecting lens system 3, and an eyepiece system 4. The eyepiece system 4 includes a focusing lens 4a's beam splitter 4b and an eyepiece 4C. Incident light from the objective lens system 2 is split by a beam splitter 4b, and is focused on an image sensor 6 through a magnifying lens system 5.

This image sensor 6 may be, for example, a COD line sensor, and is arranged so that its reading line coincides with the longitudinal direction of the leveling rod 8 shown in FIG.

The leveling rod 8 has a mark 9 having a known length, for example, 1 m, divided into n blocks 11 (for example, 10 equal parts). mark 9 so that it can be read by the image sensor 6 of the rangefinder 1.
corresponds to a portion with low reflectance (black), and the space 10 between them corresponds to a portion with high reflectance (white).

The output of the image sensor 6 is sent to the processing circuit shown in FIG. 3, and a distance value is calculated. That is, the mark/space image of the leveling rod 8 is read as an electrical signal by the image sensor 6, and is sent to the comparator 13 via the amplifier 12. The comparator 13 clips the image below a certain level E so that, for example, when the image is not in focus and the image output level is low, distance measurement processing is not performed. The output of the comparator 13 is shaped by a waveform shaping circuit 14, and then
15.

The CPU 15 calculates the distance to the leveling rod 8 based on the measured value of the interval between the marks 9 and the corresponding known length on the leveling rod 8. The measured distance value is displayed as a digital value on the display section 16 of the rear panel of the range meter 1, as shown in FIG. It is also possible to transfer the measured values from the I10 port 17 of the R3232C model to a data terminal such as a pocket computer.

The calculation of the distance is performed by utilizing the fact that the size of the image on the imaging surface of the image sensor 6 expands and contracts depending on the distance. The size of the image shrinks in inverse proportion to the distance.

That is, as shown in FIG.
Let A be the distance to the inverted image 7 by the objective lens system 2, B be the distance to the inverted image 7 by the objective lens system 2, and f be the focal length of the objective lens system 2. Then, the magnification U is as follows. Further, if the magnification from the erecting lens system 3 through the eyepiece lens system 4 and magnifying lens system 5 to the imaging surface is V, and the known length on the leveling rod 8 is LO, then the distance on the imaging surface of the image sensor 6 is The corresponding flaw length l is −f. If the number of bits corresponding to the flaw length that could be read by the image sensor 6 is X, and the pitch of the light receiving elements along the reading line of the image sensor 6 is p, then the flaw length l is 1 = X X p -- ------
-----(5). From the fourth and fifth equations above, the measured distance A can be calculated by -p.

In reality, the number of bits of the image sensor 6 is, for example, 5000.
Since it is finite like bits, the second
Even if the image corresponding to the entire length of the leveling rod 8 in the figure falls within 5000 bits, the image is enlarged at short distances, so the 5o
What can be read with the oo bit is a part of the leveling rod 8. Therefore, the known length Lo on the leveling rod 8 is the length of the unit block 11 L (for example, 0.1 m), and the number of blocks 11 that can be read by the image sensor 6 is n (1, 2 ------- −
--) Then, it is necessary to make it variable as L, = nL-・-・--・-・ (7). That is, at the farthest distance, the known length of the object to be measured is, for example, IOL (1 m), and at the shortest distance, it is I L (0,1 m). Therefore, the sixth equation becomes:

Next, the procedure for detecting X (the number of bits read by the image sensor 6 corresponding to the flaw length) and n (the number of imaged blocks) in Equation 8 based on the image output will be explained based on FIGS. 5 to 7. do.

As shown in the detection circuit of FIG. 5 and the time chart of FIG. 6, the image on the image sensor 6 (FIG. 6A) is transferred, read out based on the lock CP, and output as an image (FIG. 6B).
At the same time, the transfer lock CP is counted by the bit counter 20, and the counted value X is taken as the scale in the longitudinal direction of the image. On the other hand, the image output is supplied to an edge detection circuit 21 to detect, for example, a rising edge as shown in FIG. 6C,
The output X of the focus counter 20 is sent to the launch circuit 22 for each edge as Xo, Xt, Xz--- as shown in the sixth figure.
Latch as 1-...-. In the example shown in FIG. 6, the entire bit range of the image sensor 6 includes three blocks 11.

Bit values of each edge obtained by the latch circuit 22
By supplying -...- to the arithmetic circuit 23 and subtracting the minimum value from the maximum value, the number of bits X (image bit number) of the flaw length corresponding to n blocks can be obtained. Further, by counting the output of the edge detection circuit 21 with an edge counter 24, the number n of blocks can be obtained. Note that n is actually the value obtained by subtracting 1 from the count value of the edge counter 24.

The edge to be detected may be a falling edge as shown in FIG. 6E, and in this case as well, the bit values Yo, Y
The number of bits of the flaw length can be obtained by subtracting the minimum value from the maximum value of +, Yz'-.

FIG. 7 shows the procedure of distance calculation performed by the CPU 15 in FIG. First, in step S1, the calculation register is reset, in step S2, it is determined that the transfer lock has been advanced by one, and in step S3, the bit count value X is set to +1. In the next step S4, it is determined that the image output Q has changed from 0 (low) to 1 (high) and edge detection is performed. When an edge is detected, the bit count value X is read into the register Xn in step S5, and the edge count value n is incremented by one. The above processing is performed using the bit count value
This process is repeated until the maximum number of bits of the image sensor 6 is reached.

The finally obtained edge bit value X, ,X,,X,
−・・−・−・− Image bit number X−X□X −
X 1lifi and the number of blocks n are calculated in step S7. Furthermore, in step S8, the distance A is calculated by substituting X and n into the previously described equation 8, respectively.

If necessary, the measurement accuracy may be further increased by taking the average value of the plurality of measured values A in step S9.
Furthermore, measurement accuracy may be increased by performing a true value test based on a predetermined algorithm. If an error occurs in the true value test, for example, error display 1 will be displayed on the display section 16 in FIG.
Display 6a.

Measurement errors tend to occur as quantization errors when the flaw length is read by the image sensor 6 having a finite number of elements. Therefore, as shown in FIG. 3, the parallel glass plate 18 provided on the front side of the image sensor 6 is tilted by an actuator 19 by a minute angle, and the image position is shifted by a minute amount along the reading line of the image sensor 6. It is best to take measurements twice and average them. It is desirable to randomly change the shift amount for each measurement so that the image shift amount does not match an integral multiple of the element pitch p of the image sensor 6.

Erroneous measurements are likely to occur due to noise interference in the edge detection circuit at step $4 in FIG. Noise may be caused by dirt on the leveling rod 8 or dirt in the optical system, in addition to electrical noise on the image output. It is thought that these disturbance noises have no regularity. Therefore, as a truth value test algorithm, for example, in FIG. 6, the bit length of each block X3
An effective method is to test whether Xo matches with an error of ±1 bit. Or Yl X3, YZ X
t, Y+ -Xt, Yo -Xo 1, that is, the matching of the bit lengths corresponding to the mark 9 of each block may be seen.

FIG. 8 (A) shows a more preferred embodiment of the marks 9 to be attached to the leveling rod 8. The marks 9 are made from a wide par 9a (corresponding to logic "1"), a narrow bar 9b (corresponding to logic "0") and a space 9C. This barcode has the function of a mark representing the block length as well as an identification symbol (ID code).If this barcode mark 9 can be correctly decoded by a decoder, , detects the edge of mark 9 with high accuracy (in this case, the front end of the leftmost bar 9a)
This increases the reliability of image bit number data. This prevents images of dirt on the surface of the leveling rod 8, background behind the leveling rod, etc. from being erroneously captured.

The identification symbol indicated by the barcode mark 9 is, for example, "10".
It may be a 4-bit or more code such as "01".It is preferable to use a symmetrical bit pattern so that there is no problem even if the top and bottom of the staff 8 are reversed.Bar code code system Examples include 3 of 9 code, 2 of 5 code F, and NRZI- code used for industrial or commercial purposes.
You can use the following.

FIG. 9 shows a data processing procedure when code marks are used. First, initialization is performed in step S1, and counting of transfer lock CP and edge detection of image output (FIG. 8B) are performed in steps S2 and S3. In this case, as shown in FIG. 8C, both the rising and falling edges of each bar 9a, 9b are detected. Every time an edge is detected, in step S4 the bit count value
Take in as Z,, Z2...------. k
This process is continued until the barcode reaches 7, that is, the end of the barcode, and when it reaches 7 in step S5, the data Zo~
Decoding processing is performed in step S6 based on Z7.

In the decoding process, the bar image width Z+ Zo, Z3
Zz, Zs Z4, Z? Calculate each Zb,
Individual size comparisons are made with a predetermined error margin to identify code pit rows. At this time, if whisker-like noise is included in the image output, the pulse width discrimination algorithm determines that it cannot be decoded, so error processing is performed as a misreading.

Once the decoding is complete and the code pit string is obtained, the next
In step S7, the identification symbol (ID) “100
1” is determined.

Therefore, even if an erroneous reading occurs due to dirt on the leveling rod 8, if it does not match the ID, error processing is performed.

Once the ID code has been identified, Z is the first value Z of the register in step S9. is taken into the Xn register (XO for the first time) as the edge image bit value.

Since it has already been determined that mark 9 is the correct code, it can be said that the value Z0 is a value that indicates the leading edge position of mark 9 with high accuracy.

Next, in step SIO, it is determined whether the bit count value conduct. As a result, the bit value X of the edge of mark 9 for each block 11
0, Xl, X2--m---- are obtained in order, and the number of blocks n is counted.

When all bits of the image sensor 6 have been read, the number of bits of the flaw length
Then, the number of blocks n is calculated (step 511), and the distance A is calculated (step 512).

In addition, in the process of FIG. 9, if the image bit value X-1Xb corresponding to at least two mark edges is obtained, the image width X b X- can be calculated, so the code between X and Xb can be calculated. Regarding marks, even if a barcode decoding error or ID error occurs, the corresponding code mark may be ignored. In this case, if the block in which the error occurred is also included in the number of blocks n, the distance A can be calculated from equation 8. However, since there is a possibility that the counted number of blocks n may result in an error, it is preferable to calculate n using the following procedure.

That is, in step S9 of FIG. 9, the bit value X of each edge
,, -Xo, Xl, Xi ---------When one is obtained, the flaw length X is obtained as X=X□8-X□a, as described above. Also, the flaw length XL of one block is defined as the difference between adjacent data, XL = X, l-X.

You can get it at Therefore, the number n of image blocks that have entered the imaging plane can be calculated as n=X/XL. When a plurality of differences between adjacent data are obtained, it is possible to perform a true value test of XL by determining whether or not each of them matches.

Instead of finding the scratch length XL of one block above from X, , the image width of the wide bar 9a or narrow bar 9b in FIG. -2. Alternatively, it may be calculated using Z:lZz, etc. In this case, the length on the leveling rod 8 will be one block longer (see Figure 2).
Wide par 9a or narrow bar 9 on leveling staff 8
If the ratio of the width to b is known, it is easy to calculate the flaw length XL of one block from the image width of the bar. Bars 9a, 9b
It has already been determined in steps S6 and S7 in FIG. 9 that the image is not pseudo data, so the image width Z r Z
The probability that o etc. is the true value is very high.

In order to determine the number n of blocks included in the imaging plane with even higher accuracy, a leveling rod 8 with block addresses as shown in FIG. 10 can be used. That is, barcode mark 9
is composed of an ID code and block addresses AD0, 1.2--...--, which are different for each block. If the ID code and block address AD can be decoded, subtract AD, □-AD, .
By performing □, the number n of blocks included in the flaw length X can be determined. When decoding address barcodes,
Noise that cannot be read as a barcode is eliminated, so
The true value accuracy of the calculated value of n is extremely high.

If the image is taken with the midpoint of the leveling rod 8 always substantially aligned with the midpoint of the reading line of the image sensor 6, a leveling rod 8 with a block address as shown in FIG. 11 can be used. In this example, the length of the unit block on the leveling rod is L/2, and the pair of 2 blocks is symmetrical with respect to the midpoint 0 of the leveling rod 8, and the known lengths of the units are 2L, 3L...・Let them represent. The block address attached to mark 9 is also related to the midpoint 0.
・Make it a symmetrical shape like −・−1−−−. The scratch length x is calculated using the mark edge bit count value Xn as described above.
Based on ax%Xaia. The number n of blocks included in the imaging range matches the corresponding address of the block that obtained X mh% or X win.

An example will now be described based on the above embodiments.

In the 8th equation, the focal length r of the objective lens system 2 is 150
m, the image magnification ■ from the royal lens system 3 to the imaging surface via the magnifying lens system 5 is 20 times, and the pitch of the light receiving elements of the image sensor 6 is 7 μm. and staff 8
If the above known length LO = nL is 1 m (10 blocks of 0.1 m width) and the maximum measurement distance A is 100 m, the flaw length on the imaging surface of the image sensor 6 is approximately 301 m (
(4th equation), and the corresponding image bit number X is approximately 4286 bits according to the eighth equation. Therefore, the total number of bits of the image sensor 6 is 5000 bits (reading line length approximately 35 cm).
stipulated in At this time, the distance measurement error corresponding to the quantization error of ±1 bit is 100m above 2 by 100m/4286.
It is 3 cm. When the distance A is 50 m, the total flaw length is about 60 m, and the number n of blocks that can be imaged is half, ie, 5. The image bit length corresponding to 5 blocks (0.5m) remains unchanged at 4286 bits, and the distance measurement error is approximately ±1c.
m.

The closest distance is approximately 1 m when one block (0,1 m) is read with 5000 bits or less.

If you get closer than this, the image will overflow. The accuracy at this time is approximately ±2N. Increasing the number of block divisions will increase short-range ability.

A bar code mark 9 such as that shown in FIG. 8 can also be read with the device of the above-mentioned constants. That is, the width of the narrow bar 9b is 0.5 cm (1/20 of L block length 10 cm)
Then, when the distance is 100m, the image width is 4286÷2
00 is equivalent to about 20 bits and can be read satisfactorily. In this case, the total number of modules of barcode mark 9 is 10 (
If the narrow bar 9b and the space 9C are 1, and the wide bars are 2 to 3, the total width of the mark 9 is approximately 5 cm, which falls within one block (10 cm).

By increasing the overall length L0 of the leveling rod 8, increasing the telephoto magnification, and increasing the number of bits of the image sensor 6, it is possible to measure even further distances or measure with higher precision.

The above has been explained based on the preferred embodiments of the present invention, but
Various modifications can be made to the embodiments based on the technical idea of the present invention. For example, a two-dimensional array sensor can be used as the image sensor 6. Furthermore, an image pickup tube or the like may be used as the image sensor in addition to the COD. A plate-shaped body on which marks 9 are printed may be attached to the target as the leveling rod 8.

Alternatively, a leveling rod whose blocks are alternately color-coded as shown in FIG. 12 may be used. In this case, mark 9 and mark 1 in FIG.
The block 11 in FIG. 2 is combined with the block 11 in FIG. In addition, in FIG. 12, the barcode corresponding to mark 9 is placed in each block 11.
It may be added to the edge part of. For white and black blocks, the color coding of bars and spaces in the barcode is reversed.

Note that when measuring distance using the distance meter of this example,
The surveyor looks into the eyepiece 4c and brings it into focus.
Since the focal point differs depending on individual differences, an automatic focusing method may be used. For example, a focusing lens motor and a servo circuit that perform servo operation so that the differential level of the image output of the image sensor 6 is maximized can be added.

〔Effect of the invention〕

According to the distance measuring method of the present invention, it is possible to measure distance with relatively high accuracy using a telephoto optical system and a t-most image means with a relatively simple configuration.

Furthermore, according to the rangefinder of the present invention, the known length on the leveling rod automatically changes between long and short distances, so when the scratch length is small at long distances, the number of blocks can be increased to make the ↑most image range effective. Even if the flaw length becomes large at a short distance, the number of blocks can be reduced and the measurement can be made without exceeding the effective imaging range.

Further, according to the distance measuring leveling rod of the present invention, it is possible to process the image output signal while distinguishing it from a false image source by using the code pattern attached to each block, thereby making it possible to eliminate measurement errors as much as possible.

[Brief explanation of drawings]

Fig. 1 is a route map of the optical system of a rangefinder to which the present invention is applied, Fig. 2 is a route map of a measuring staff, Fig. 3 is a processing circuit diagram of image output, and Fig. 4 is a rear view of the rangefinder. Figure 5 is a distance measurement circuit diagram, Figure 6 is an image bit measurement time chart, Figure 7 is a flowchart of the distance measurement procedure, and Figure 8 is an image and measurement time when the mark on the staff is converted into a bar code. Figure 9 is a flowchart showing the measurement procedure in the case of a barcode, Figure 10 is a route map of a leveling staff with block addresses, Figure 11 is a route map showing another example of a leveling staff with block addresses, and Figure 12 is a leveling staff. It is a route map showing another example of the mark. In addition, in the symbols used in the drawings, 1.
−−−−−−−−−・−−1−−1 Objective lens system 3−−
−−−−1・−・−−1−−−・Erection lens system 4−・−
・−・−・・・−−1−−Eyepiece system 5−・−・・・
・・・・・・−Magnifying lens system 6−−−−−−1...−
・・−・−Image sensor 8−・−・−・・・−・−
・・・−・Staff 9～・−・・・・・・・−・−・? −
11...--------1111 block.

Claims (1)

[Claims] 1. A target of a known length is imaged by a telephoto imaging means, an image length of an imaging surface is calculated based on the image output signal, and an image is taken from the above-mentioned known length, image length, and objective lens. A distance measuring method characterized by calculating and obtaining the distance to a target based on a telephoto magnification that reaches a surface. 2. telephoto imaging means for imaging a target of known length consisting of a plurality of rows of blocks each representing a unit length; and means for measuring the image length of the said block row on an imaging surface based on an image output signal; , a rangefinder comprising means for detecting the number of blocks included in the image length, and calculation means for calculating the distance to the target based on the known length, the image length, the number of blocks, and the telephoto magnification. 3. A patent claim characterized in that the means for measuring the image length comprises means for detecting front and rear edges of the image output signal, and counting means for quantifying the interval between edges by counting predetermined clock pulses. Rangefinder according to item 2. 4. The telephoto imaging means comprises a telephoto optical system and a solid-state imaging device arranged on the optical axis thereof and having a light receiving element array of a predetermined number of bits in the direction of the block row. Rangefinder described in item 2. 5. A plurality of consecutive blocks each having a mark having an interval such that the image length can be measured based on the image output signal when an image is captured by the imaging means, and each of the marks represents a unit length. A leveling rod for measuring distance, which comprises a column and each block is provided with a code pattern that can be distinguished from a pseudo video source. 6. The distance measuring level rod according to claim 5, wherein the mark consists of the code pattern. 7. The distance measuring level rod according to claim 5, wherein the code pattern includes a block address code for distinguishing each block from others.