JPH1062119A - Device and method for measuring position - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable position measurement without being influenced by enlargement and contraction or a position angle of a bar code by a method wherein at least two bar code readers are arranged apart at a predetermined distance, and measurements are made based on respective scanning amounts. SOLUTION: A bar code 11 of a bar code label 11a is a distribution bar code, and the bar code 11 is structured so as to be scanned by two bar code readers 12a, 12b. An interval between these two bar code readers 12a, 12b, namely an interval between respective scanning centers is W. These respective bar code readers 12a, 12b have a laser beams source and a polygon minor or a tilt mirror, and the bar codes are optically scanned and irradiated by the laser, so that reflection signals obtained from the bars or spaces constituting the bar code 11 are shaped, thereby obtaining code information by decode functions. These bar code readers 12a, 12b measure a scanning amount at a timing decoded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position measuring device and a position measuring method used for traveling control of a transport vehicle and cargo handling control by a robot hand.

[0002]

2. Description of the Related Art As a positioning device in the field of logistics, a device for reading the presence of a code line such as a bar code using a linear scanner and performing three-dimensional relative position measurement is known from Japanese Patent Laid-Open No. 6-124359. Have been.

[0003]

The above-mentioned prior art apparatus has a function that a bar code originally has, that is, information is represented by coding (bar coding), and the information is read using a reader. Has no function. Further, the code system is a method that cannot enjoy the advantage of excellent compatibility between hardware and software standardized by JIS.

[0004] Specifically, in the "guidance of an automatically controlled vehicle" described as an application in the above-mentioned conventional technology, it is accelerated to know location information uniquely indicating a traveling place and a current position of the vehicle. It is necessary for traveling control such as deceleration and stop, and incorporating the information in a barcode in advance is effective because it is not necessary to separately prepare equipment and devices for knowing the information. It is not realized by the conventional technology.

[0005] In "automatic control of lifts on loading shelves", if the identification numbers of products, pallets and shelves are incorporated as barcode information, it is possible to confirm the cargo handling target, which is effective for lift positioning control. With a function that uses only a position measurement code, the position of the entire system, such as what the measurement target code is installed in, what kind of positional relationship is installed, and what kind of load is loaded No information is available.

As described above, it has been described that the barcode is not only a function as a mark for position measurement, but that incorporating information is effective for automatic control. Next, the barcode is generally used for distribution management. The following describes that it is useful to target a barcode for position measurement.

In recent years, bar codes themselves have been standardized and standardized (for example, JIS X0501 and X05).
02, X0503 and the like. Hereinafter, such a barcode is referred to as a “distribution barcode”), and distribution management using the distribution barcode has been developed. The decoding method of the barcode reader also complies with the standard of the distribution barcode. A system using a distribution barcode has been standardized and has been spread from upstream to downstream in distribution, so it can be obtained at a low price. And not only the reader but also a distribution barcode printer, a distribution barcode inspection machine, and a distribution barcode label pasting machine conform to the above standards. Also, transport,
The product itself, which is the object of cargo handling, is already printed as a distribution management means on the product or the case where the product is packed.

In such an environment, if the distribution barcode can be used not only as information on the product to which the barcode is attached but also as a target for position measurement, hardware and software can be obtained at low cost and compatibility can be improved. In addition, it is possible to enjoy the advantage that the already provided barcode can be used as it is.

However, the above-mentioned conventional technique (Japanese Patent Laid-Open No.
As described below, there are various technical problems in applying the positioning device disclosed in JP-A-124359) to a distribution barcode.

(Problem 1) A problem concerning the measurement of the separation distance Z between the bar code label 1 and the linear scanner 2 shown in FIGS. 1 and 2 will be described below.

1- (1) To measure the separation distance Z to the barcode label 1 on which a barcode or the like is printed, the distance Lr between two bars a and b separated in the scanning direction is known. There must be. There is no problem if a barcode designed exclusively for position measurement is used. However, when a distribution barcode is targeted, the distribution barcode can be enlarged or reduced during printing. , B, it is necessary to check the dimensions or the enlargement / reduction ratio of each individual transported object in order to satisfy the condition that the distance Lr is known.

For example, in the case of a bar code symbol for a common product, enlargement and reduction in a range of 0.8 to 2.0 times are permitted (JIS X5001 5.2.2). In the case of a barcode symbol for a logistics product, 0.625 to 1.2
Enlargement and reduction are allowed in the range of double (JIS X05
02 5.2.2).

In FIG. 1, assuming that the enlargement / reduction ratio of the distribution bar code is k, the time tLr required to scan the actual bar interval Lr with the linear scanner 1 (tLr = t in FIG. 1).
₅₋ t ₂ ), where tL is the time required to scan the interval L assumed in advance, and tLr = tL × k. _(ts = t 7 _-t 1 in FIG. 1), when the actual length of all the scanning lines S, Sc = L × (ts / tLr) = L × (ts / tL) × (1 / k) = S × (1 / k) On the other hand, the calculated separation distance Zc is as follows: Zc = Sc / tanα = S / tanα × (1 / k), where α is the total scanning angle and Z is the actual separation distance, and a measurement error of 1 / k times occurs. For example, k = 2
In this case, only half of the actual distance is measured, which makes it almost impossible to perform automatic control.

In order to solve such a problem, the interval L between the individual bar codes may be known in advance.
As the trend of increasing the variety of products in small quantities increases, the number of product items handled in supermarkets has reached tens of thousands. Since it is necessary to measure or standardize the information of the dimension L for each item, it is practically difficult.

1- (2) To determine the other position, that is, the position X in the traveling direction and the position Y in the direction (height direction) perpendicular to the traveling direction, it is assumed that the separation distance Z is first obtained. If the above-mentioned problem 1- (1) cannot be solved, not only the separation distance Z but also the position X in the traveling direction and the position Y in the direction orthogonal thereto cannot be obtained.

(Problem 2) A problem relating to the position measurement in the scanning direction X shown in FIG. 3 will be described below.

The vehicle or lifter on which the linear scanner 2 is mounted runs or stops at an attitude angle with respect to the measurement line. In this case, the linear scanner 2 has an attitude angle with respect to the barcode label 1 (the vertical line on the printing surface of the barcode label 1 does not coincide with the center line of the linear scanner 2). In such a state, an error occurs in the X position measurement.

That is, in FIG. 3, the light source of the linear scanner 2 is defined as the origin 0, the center axis direction of the linear scanner 2 is defined as the Z axis, and the direction orthogonal to the Z axis is defined as the X axis. Also, the center of the barcode label 1 is P, the straight line parallel to the X axis passing through this point P is A, the two measurement code lines are C ₁ and C ₂ , and the attitude angle of the barcode label 1 with respect to the X axis. To θ, and C ₁ , C ₂
The perpendiculars drawn from the to the line A are B ₁ and B ₂ respectively.
The interval between the code lines C ₁ and C ₂ is L. The angle (Z) at which the linear scanner 2 scans to obtain reflected signals from C ₁ and C ₂
(With respect to the axis) are φ ₁ and φ ₂ , respectively.

Straight lines having angles of φ ₁ and φ _{2 with} respect to the Z axis and passing through the origin 0 are defined as U ₁ and U ₂ , respectively, and straight lines U ₁ and U 2
The intersections between ₂ and the straight line A are C ₁ ′ and C ₂ ′, respectively.
The midpoint between C ₁ ′ and C ₂ ′ is P ′. No attitude angle (θ
= 0), C ₁ and C ₁ ′ and C ₂ and C ₂ ′ coincide, and P = P ′ coincides, so that there is no problem in X position measurement.

However, when the posture angle θ exists,
Since it is unknown that the attitude angle θ exists in the linear scanner 2, the measurement code lines are not C ₁ and C ₂ , but C ₁ on the straight line A parallel to the X axis at the separation distance Zr. ', C ₂ '. Therefore, the X position is not the X coordinate of the point P,
It is measured as the X coordinate of the point P '.

Here, since the length of the line segment C ₁ -C ₂ is L and the attitude angle is θ, the length of the line segment B ₁ -B ₂ is L × cos
θ, the angle C ₁ ′ · C ₁ · B ₁ is φ ₁ , and the line segment C ₁ -B
_Since the length of ₁ is (L / 2) × sin θ, the line segment C ₁ ′
The length of -B ₁ becomes (L / 2) sinθ × tanφ 1.

Similarly, the length of the line segment B ₂ -C ₂ ′ is (L /
2) × sin θ × tan φ ₂ and thus the line segment C ₁ ′
The length of −C ₂ ′ is the line segment (C ₁ ′ −B ₁ ) + the line segment (B ₁
−B ₂ ) + line segment (B ₂ −C ₂ ′) = L × cos θ + (L
/ 2) × sin θ × tan φ ₁ + tan φ ₂ ).

On the other hand, the length of the line segment PC-2 'is
B ₂ ) + line segment (B ₂ −C ₂ ′) = (L / 2) × cos θ
+ (L / 2) × sin θ × tan φ ₂ Therefore, assuming that the coordinates of the point P are P (PX, PZ), the coordinates of the point C ₂ ′ are C ₂ ′ (PX − ｛(L / 2) × cos θ + (L / 2)
× sin θ × tan φ ₂ ｝, PZ). Here, the point P '(PX', PZ ') is X coordinate PX' and is equal to a value obtained by adding half the length of -C ₂ '' line _C 1 in the X-coordinate of 'point _{C 2,} PX '= PX - {(L / 2) × cosθ + (L / 2) × sinθ × tanφ 2} + (1/2) × {L × cosθ + (L / 2) × sinθ × (tan φ 1 + tanφ 2) ＝= PX− (L / 2) × sin θ × tan φ ₂ + (L / 4) × sin θ + (tan φ ₁ + tan φ ₂ ) = PX + (L / 4) × sin θ × (tan φ ₁ -tan φ ₂ )

It can be seen that ΔPX = PX'-P
X, that is, the error ΔPX of the X position that can be measured by the presence of the posture angle θ is ΔPX = (L / 4) × sin θ × (tan φ ₁ −tan φ ₂ ).

(Problem 3) Regarding the position measurement in the direction Y orthogonal to the scanning direction, the position in the bar longitudinal direction is 0 degree or 9 degrees.
A bar c having an angle other than 0 degrees is required, and such a bar does not exist in the distribution barcode. Therefore, the Y position cannot be obtained.

(Problem 4) Since the role of the code line is determined depending only on the order of the code lines in common to the X, Y, and Z position measurement, 4- (1) if there is a black spot stain, An erroneous determination as a code line causes a position measurement error. 4- (2) When a plurality of barcode labels exist in the scanning range, the second and subsequent barcode labels are ignored. 4-
(3) If the entire barcode label does not fall within the scanning range, an error occurs in the order determination of the code lines, or the measurement is not completed. 4- (4) Since there is no error check function, a position measurement error cannot be determined, and it is difficult to use the position as feedback for automatic control. I have each problem.

In addition, in the field of semiconductor manufacturing, "a method for detecting the position of a non-exposed material in electron beam exposure" (JP-A-55-160428), and in the printed matter inspection field, "printed matter" (JP-A-63-72069). ) Discloses a method of measuring the X and Y positions of a code, but application to a distribution barcode is very difficult for the same reason as described above. These documents do not disclose the Z position measurement.

In the field of physical distribution, in addition to the above-mentioned "positioning device" (Japanese Patent Application Laid-Open No. 6-124356), there is an "automated guided vehicle" (Japanese Patent Application Laid-Open No. 62-93712). , And no mention is made of the Y and Z position measurement.

[0029]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances.
At least two bar code readers are set apart from each other by a predetermined distance, measurement is performed based on the respective scanning amounts, and the scanning amount is determined by a scanning angle until a predetermined code is detected.

Regarding the problem 3, the position is determined based on the result of the raster scan check digit determination.

Regarding the problem 4, the scanning amount of the bar code reader is determined by the decode signal. In addition, the check digit judgment result is notified to the outside,
Alternatively, the output is not updated based on the check digit determination result.

[0032]

In the prior art, two points were required on the barcode and the interval had to be known. On the other hand, in the position measuring device and the position measuring method according to the present invention, At least two barcode readers were set apart by a predetermined distance. This installation interval is known. What this means is that the barcode reader has parameters that existed in the conventional barcode geometric information. As a result, only one point is required on the barcode side, and the barcode is not affected by the enlargement / reduction of the barcode or the attitude angle.

In the position measuring device and the position measuring method according to the present invention, a code set in advance or set by automatically discriminating the type of barcode symbol is used up to the timing when the decoding result is obtained. The scanning amounts of the two barcode readers are obtained. The set code is a group consisting of a plurality of bars and spaces.
The timing obtained from the decoding result is the end point of this code. Since the position is measured based on the scanning amount from the scanning start point to the code end point (one point on the bar code), two bars are provided on the bar code side. Eliminates the need for code wires. Therefore, it is not necessary to know the interval between the two code lines in advance, and the bar code is not affected by enlargement or reduction of the bar code. Also, even when the bar code and the bar code reader have an attitude angle, instead of measuring the position based on the positions of two points on the bar code as in the related art, one point on the bar code is used. Since the position is measured based on the end point of the code, the position angle is not affected.

On the other hand, the check digit determination result of the raster scan is obtained for each scan. Of the plurality of check digit determination results obtained, the result of the check digit determination when scanning the area where the barcode exists is OK.
(Successfully read successfully), and the check digit determination result when scanning an area where no bar code exists is NG (cannot be read or read data contains an error). From this, if the check digit determination result finds the center of the OK raster scanning area, the Y position of the barcode can be known. In one raster scan, the center between the first OK position and the last OK position may be obtained. This gives 0 degrees or 9
A bar having an angle other than 0 degrees is not required, and position measurement using a distribution barcode becomes possible.

Since the scan amount up to the predetermined code is obtained, the probability of erroneous determination due to dirt can be extremely low as compared with a method of finding a scan amount by simply finding a code line.
The position measurement does not depend on the order in which the code lines exist, and there is no problem in the position measurement even if code lines having other purposes than the position measurement are mixed.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the prior art shown in FIGS. 1 and 2, two code lines a and b for measuring the Z and X positions are used.
And a bar code label 1 composed of a code line c having an angle for measuring the Y position, and one linear scanner 2. What should be noted here is that the barcode is exclusively used for position measurement.

FIG. 4 et seq. Show an embodiment of the present invention.
The barcode 11 of the barcode label 11a is a distribution barcode, and the barcode 11 is scanned by two barcode readers 12a and 12b. The interval between the two barcode readers 12a and 12b, that is, the interval between the respective scanning centers is W.

In this embodiment, each of the bar code readers 12a and 12b has a laser light source and a polygon mirror or an oscillating mirror. The reflected signal obtained from the bar or the space that constitutes it is shaped, and code information is obtained by a decoding function. The bar code readers 12a and 12b also have a function of measuring a scanning amount at the timing of decoding.

The bar code reader 12 in this embodiment
Reference numerals a and 12b each include a laser light source and a polygon mirror or an oscillating mirror, and optically scan and irradiate a bar code with a laser beam to shape a reflection signal obtained from a bar or a space constituting the bar code 11. Up to this point, it has the same function as the linear scanner in the prior art shown in FIGS.

The method of measuring the distance Z between the barcode readers 12a and 12b and the barcode 11 and the position X in the scanning direction by the barcode reader will be described below with reference to FIG.

The origin of the coordinates is set to 0. This is a bar code reader 12 installed at a distance W in the X-axis direction.
a, 12b. The Z axis is orthogonal to the X axis. In addition, each bar code reader 12
Let the scanning center points of a and 12b be 0 ₁ and 0 ₂ . further,
Barcode label 11 on which barcode 11 is printed
a is placed at an angle to the X axis. Here, angles at which a point P on the barcode label 11a is viewed from each of the barcode readers 12a and 12b are φ ₁ and φ ₂ respectively.
And

Here, for the sake of simplicity, each angle is represented by an angle from the Z axis. For this reason, the scan angle does not match, but the angle formed by the scan start angle and the Z axis is a value unique to the barcode reader. That is, as shown in FIG. 6, assuming that the scan start angle is θs and the angle (scan angle) when the point P is seen from the start of the scan (scan angle) is θs (known) + θp
Since (measured value) + φ ₁ = barcode reader unique value, φ ₁ can be easily obtained.

The point P on the barcode label 11a is located at a distance of Z from the X axis. A straight line that passes through the point P and is parallel to the X axis and the center axis of each barcode reader 12a, 12b (Z
The intersection of the axis and parallel) respectively and _B 1, _{B 2.}

First, paying attention to the triangle 0 ₁ · P · B ₁ , Z = length of the line segment P−B ₁ / tan φ ₁ , and paying attention to the triangle 0 ₂ · P · B ₂ , Z = line minute _{P-B 2} becomes long / tan [phi _2. On the other hand, W = length of the segment _{P-B 2} - since the length of the line segment _{P-B 1, W = Z} × (tanφ 2 -tanφ 1) , and the _{thus, Z = W / (tanφ 2} - tanφ ₁ ). Also with respect to the X, it can be calculated as X = W / 2 + line _{P-B 1 = W / 2} + Z × tanφ 1 = W / 2 + (W × tanφ 1) / (tanφ 2 -tanφ 1). In this method, it is important that the barcode label 11a does not need to be parallel to the X axis.

The method for obtaining the point P must also be explained. Generally, inside a barcode reader, a reflected signal from a distribution barcode is decoded to determine a star code, a center code, a stop code, a manufacturer-specific code, a product-specific code, and the like. Specifically, a thick / thin judgment threshold is set based on the width of the bar or space of the start code portion scanned after the quiet zone (white zone scanned before the bar code), and the code of the start code itself is set. Depending on the pattern, the type of barcode symbol, for example, JAN, NW-7, IT
F and the like are identified and specified. Here, the point P is obtained by decoding the center code as a JAN code.
The method for obtaining is described. In the JAN code,
The start code is also called a left guard bar, the center code is also called a center bar, and the stop code is also called a right guard bar.

The operation will be described below with reference to the flowchart shown in FIG. First, a quiet zone (white area having a certain width or more: reflection) is detected, and a start code appearing thereafter is received. The reflection time of the first bar of the start code is regarded as one bar, and the time is set as a threshold for determining the continuous number of bars or spaces.

Thereafter, when the start code is "101" (a combination of one bar + one space + one bar), it is determined that the JAN code is targeted. In the case of other codes, it is determined that the code symbol is not JAN, and the flow shifts to another decoding flow. Furthermore, a code for 6 characters following the start code, that is,
Since one character is composed of 7 modules (1 module is equivalent to one bar or space), decoding of 7 modules × 6 characters = 42 modules is performed, and the codes of the manufacturer and the product are known. Since this decoding method is already known by general bar code scanners, it will not be described here.

This is followed by the center code. The scan amount is latched at the same time when the center code "101" is recognized. Specifically, as shown in FIG. 13, a comparison 3-bit register 13 is prepared in advance in a barcode reader, and "101" is set. Laser light source 14, polygon mirror 15 driven by motor with encoder
And the signal reflected from the barcode 11 is
It is also amplified from the laser receiving unit 16 through the amplifier 17,
The signal is compared with a reflection intensity threshold value 19 set in advance by a comparator 18.

As a result, 0 is set for a space (white: with reflection), 1 is set for a bar (black: no reflection), and input 3
The data is input to the bit shift register 20. Here, if the contents of the comparison 3-bit register 13 and the input 3-bit shift register 20 match, a center code detection timing is generated and input to the scanning angle counter 21. The center code detection timing is generated when the next point P, scanning angle at that time is obtained detect and phi ₁ and θp with a rotational angle detecting means such as an encoder or potentiometer, for example, the rotation angle of the polygon mirror 15. Here, the mirror is not limited to a rotary type, but may be a vibration type swing mirror instead of a polygon mirror. If the rotation speed can be considered to be constant, the rotation angle detection means may count the rotation time using a clock.

[0050] Similar operations obtain phi ₂ is also performed by other bar code readers. Then, according to the above formula, Z
And the position of X.

As described above, since the scanning amount is obtained at the decoding end point of the predetermined code, the probability of erroneous determination due to dirt can be extremely low as compared with a method of finding a scanning amount by simply finding a code line. The position measurement does not depend on the order in which the code lines exist, and there is no problem in the position measurement even if code lines having purposes other than the position measurement are mixed.

Next, a method for obtaining the Y position will be described. As shown in FIG. 7, raster scanning in which scanning lines are gradually shifted in the longitudinal direction of the barcode 11 is used. That is, a plurality of scanning lines can be drawn in the Y direction. In a region where the barcode 11 exists, the determination result OK can be obtained by determining the check digit originally possessed by the barcode 11, but in a region where the barcode 11 does not exist, the determination is OK. No result is obtained. In this case, since the decoding has not been successful, the determination result is NG. When the scanning direction is not orthogonal to the longitudinal direction of the barcode 11, only a part of the barcode 11 is caught on the scanning line, and the determination result is NG. As a result, as shown in FIG. 8, the determination result is divided into two types of areas, OK and NG. The Y position can be obtained from the bar code longitudinal scanning amount when the result of this determination is OK. The flowchart is shown in FIG.

[0053] to set the raster scanning angle H ₁ when the judgment result becomes OK past the area of the NG. At this time, if OK has been obtained from the beginning, an error occurs in the Y position measurement because the OK area and the upper end have not been detected, but there is no problem with the intended automatic control. This is because the movement of the portion on which the bar code reader is mounted is controlled with the center of the bar code as a target, so that the bar code center substantially coincides with the bar code reader central axis due to the movement. This is because, in this state, the above-described OK area is located substantially at the center of the scanning area.

Next, when it becomes NG, the raster scanning angle H ₂
Set. The two raster scanning angles H ₁ and H ₂ can be measured by a raster rotation angle detector attached to a polygon mirror (not shown) driving the raster scanning or a swing mirror. The Y position is calculated based on H ₁ , H ₂ and the already obtained Z. That is, in FIG. 15, the position is determined by Y position = Z / 2 × (tan H ₁ + tan H ₂ ). As described above, by using raster scanning, a bar having an angle other than 0 degrees or 90 degrees, which is required in the related art, is not required, and as a result, position measurement using a distribution barcode becomes possible. .

As described above, the Y position is obtained based on the check digit determination result. However, the Y position may be obtained from a raster scanning area that recognizes a predetermined code. As shown in FIG. 9, the location code “0” is included in the barcode.
For example, an area in which the location code “01” is recognized, in which “0”, “01”, and “10” are incorporated, may be replaced with the check digit determination result OK area. However, the determination result NG area is an area other than the location code “01”. In this case, the location code has been described, but the product code or another code may be a code that uniquely indicates a specific bar code.

In order to eliminate an incorrect position measurement result, there are the following two methods. In each case, it is determined whether the barcode information has been read normally based on the check digit determination result.

The first method is to notify the check digit determination result to an external controller, for example, a controller for automatically controlling by taking in the position output of a bar code reader. When the check digit determination result is NG, the controller internally holds the previously captured position data,
Automatic control is performed based on the previous data.

The second method is that the bar code reader itself is
This is a method in which the position output data is not updated when the check digit determination result is NG. The output register is held until the check digit determination result becomes OK.

(Embodiment 2) In Embodiment 1, two bar code readers 12a, 12a are separated from each other by a predetermined distance in the X-axis direction.
In the second embodiment, two bar code readers 12a and 12b whose positions are shifted by dZ in the Z direction are used as shown in FIG.

Referring to FIG. 11, Z according to the apparatus configuration of FIG.
And the position measurement method of X will be described. It is assumed that the center axes of the two barcode readers 12a and 12b coincide with each other and also coincide with the Z axis. First barcode reader 12
The scanning center 0 ₁ of a the origin, taking X-axis to be perpendicular to the 0 ₁ as Z axis. As in the first embodiment, the respective scanning centers 0 ₁ , 0 of the bar code readers 12 a, 12 b are set.
_The angles formed by the straight line and the Z-axis when the point P (X, Z) on the barcode 11 is viewed from ₂ are φ ₁ and φ ₂ respectively. The intersection of the straight line passing through the point P and parallel to the X axis and the Z axis is defined as a point Q.

[0061] In this case, with respect to triangle ₀ 1 · P · Q, with respect to Z = X / tanφ ₁ triangle ₀ 1 · P · Q, solving the Z + dZ = X / tanφ ₂ The two equations for X, X = dZ × tan φ ₁ × tan φ ₂ / (tan φ ₁ -t
anφ ₂₎ next, and solving for Z, it can be calculated as _{Z = dZ × tanφ 2 / (} tanφ 1 -tanφ 2).

Also in this case, similarly to the embodiment, a bar code does not require two points, and thus a bar code can be scaled up or down, and a measurement method corresponding to a distribution bar code which is completely unaffected by the attitude angle can be obtained. Can be. Note that the method for obtaining the point P and the method for obtaining the Y position are the same as those in the first embodiment, and thus description thereof will be omitted.

(Application Example 1) In FIG. 16, a label on which a position measurement mark 22 is printed is attached to a wall of a factory or a warehouse along the traveling direction of the automatic guided vehicle 23 and mounted on the automatic guided vehicle 23. An example in which the position measurement mark 22 is scanned by the barcode reader 24 has been described.

As a result of the scanning, the distance between the position measurement mark 22 and the bar code reader 24 and the relative position in the horizontal direction can be measured. Since the mounting position of the bar code reader 24 is known in advance, Automatic guided vehicle 23
Of the position measurement mark 22 with respect to the position measurement mark 22 can be known. In this application example 1, it is sufficient for control if two-dimensional position measurement of Z and X can be performed. The remaining axis, height information from the floor, is not required for traveling. In this case, what can be known is the relative position between the position measurement mark 22 and the automatic guided vehicle 23. Since each position measurement mark 22 can include an ID code or can be combined,
If information on which position of the position measurement mark with the code is affixed to the wall is stored in a memory in the controller of the automatic guided vehicle 23 (not shown) and can be referred to, the automatic guided vehicle 23 It becomes possible to know at which position on the wall the vehicle is stopped or traveling.

At this time, the position from the reference point with the wall may be directly incorporated into the position measurement mark 22 instead of indirectly knowing the position with the ID code. Information of the distance L ₁ of the distance from a reference point with a wall in Figure 16 to a position directly position measurement mark 22 is stuck is added after the mark position measurement only. Using a bar code reader 24 mounted on an automatic guided vehicle 23, the position measurement mark 22
The relative position between the position measurement mark 22 and the automatic guided vehicle 23 is determined by the mounted CPU via the installation position information of the bar code reader 24.

[0066] Since the bar code reader 24 reads also the distance L _1, the distance to the AGV 23 from the reference point S of the wall if adding the L ₁ in the relative position, i.e. the position in the building is required Will be. The automatic guided vehicle 23 performs travel control such as stop, acceleration, and deceleration based on the position information and a travel sequence programmed in advance. In addition, steering is performed so as to travel at a predetermined distance from the wall.

(Application Example 2) FIG. 17 shows an example in which a bar code 22 is attached to the shelf 26 and the pallet 25 in order to realize automatic pallet height detection useful for unloading the pallet 25. Shelf 26 containing pallets 25
The bar code 22 is attached to the center of the pallet 25, and the bar code 22 is also attached to the center of the pallet 25 (the center between the two fork insertion holes). The pallet 25 is placed so that the horizontal position of the center of the shelf 26 and the center of the pallet 25 substantially match. In addition, a bar code 2 is provided at a portion that is the root of the fork 27 and does not interfere with cargo handling.
Barcode reader 2 for scanning and measuring position
4, the bar code reader 24 can be detected by a sensor such as an encoder attached to a height mast mechanism of the bar code reader 24 from the floor.
It is assumed that the horizontal position of the fork 27 with respect to the pallet 25 is substantially positioned by means of the traveling position detection or the like.

The height of the shelf 26 is known in advance when the shelf 26 is designed, and the thickness of the pallet 25 is also determined at the time of introduction. Therefore, the fork 27 is raised to the design height of the shelf 26 by a mast mechanism (not shown). In actuality, the height of the shelf is smaller than designed because deflection occurs due to the load. Therefore, the barcode position (height) of the shelf 26 is measured using the barcode reader 24 and the height of the shelf 26 is measured. Correct the data. At the same time, the number code of the shelf 26 incorporated in the barcode 22 is read, and it is confirmed whether or not it matches the shelf number specified by the host management computer.
If they match, the cargo handling work is continued. If they do not match, error information is reported to the upper management computer and the cargo handling work is temporarily stopped. Next, the fork 22 is raised to a height obtained by adding half of the thickness of the pallet 25 to the corrected height data of the shelf 26, and the barcode 22 of the pallet 25 is
Reads the pallet identification code embedded in the pallet and checks if it matches the pallet identification code specified by the upper management computer. If the pallet identification code matches, the cargo handling work is continued. Notify the management computer and suspend the cargo handling work. Further, the position (height) of the barcode 22 on the pallet 25 is measured,
The controller for the fork operation controls the mast mechanism so that the position and the height of the fork 27 match. Also,
Although the horizontal position of the pallet 25 and the fork 27 substantially coincide with each other by another means, the horizontal position can be obtained by scanning the barcode position with the barcode reader 24 in the same manner as the height. The center of the pallet hole and the center of the fork coincide with each other by the controller performing minute movement control of the traveling portion on which the entire work machine is mounted based on the position information. 28 is a luggage. Further, the separation distance between the barcode 22 and the barcode reader 24 is measured, and the fork 27 is protruded toward the pallet hole 25a based on the distance information, so that a sufficient insertion amount can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a position measurement method in a Z direction in a conventional example.

FIG. 2 is a perspective view showing a method of measuring a position in a Z direction in a conventional example.

FIG. 3 is an explanatory diagram showing a position measuring method in the X direction in a conventional example.

FIG. 4 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a position measuring method in the Z and X directions according to the present invention.

FIG. 6 is an explanatory diagram showing a scanning angle of a barcode reader.

FIG. 7 is an explanatory diagram showing a position measurement method in the Y direction according to the present invention.

FIG. 8 is an explanatory diagram showing a state in which a barcode is raster-scanned.

FIG. 9 is an explanatory diagram showing how raster scanning is performed when a location is embedded in a barcode.

FIG. 10 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a position measuring method in the Z and X directions in the second embodiment.

FIG. 12 is a flowchart illustrating a method for calculating a position in the Z and X directions according to the first embodiment.

FIG. 13 is an explanatory diagram showing a configuration and operation in a barcode reader.

FIG. 14 is a flowchart showing a method for calculating a position in the Y direction.

FIG. 15 is an explanatory diagram for calculating a Y position based on Z by raster scanning.

FIG. 16 is an explanatory diagram showing a mark scanning method using a barcode reader mounted on an automatic guided vehicle.

FIG. 17 is an explanatory diagram showing a mark scanning method using a barcode reader attached to a fork.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Label 2 ... Linear scanner 11 ... Barcode 11a ... Barcode label 12a, 12b, 24 ... Barcode reader 13 ... 3-bit register 14 for comparison 14 ... Laser light source 15 ... Polygon mirror 16 ... Laser receiver 17 ... Amplifier 18 ... Comparator 19 ... Reflection intensity threshold 20 ... Input 3 bit register 21 ... Scan angle counter 22 ... Position measurement mark 23 ... Automatic guided vehicle 25 ... Pallet 26 ... Shelves 27 ... Fork

Claims (8)

[Claims] 1. A position measuring device for measuring a relative position between a bar code and a bar code reader, wherein the position measuring device is directed to a scanning target, and is arranged at a predetermined distance in a distance from or near the scanning target. Characterized in that at least two bar code readers are installed. 2. A position measuring method for measuring a relative position between a bar code and a bar code reader, the method comprising the steps of: scanning a plurality of bar code readers up to a measurement reference point on a bar code (scan angle); A position measuring method, wherein a position of a barcode is determined. 3. The position measurement method according to claim 2, wherein a predetermined decode signal is used as a measurement reference point. 4. The position measuring method according to claim 2, wherein a type of the barcode symbol is automatically identified, and a decode signal is selected for each barcode symbol. 5. A position measuring method for measuring a relative position between a barcode and a barcode reader, wherein a position in a direction orthogonal to the raster scanning is determined based on a check digit determination result of the raster scanning. And the position measurement method. 6. A position measuring method for measuring a relative position between a barcode and a barcode reader, wherein a position in a direction orthogonal to the raster scan is determined based on a result of raster scan decoding. Position measurement method. 7. The system according to claim 2, wherein a check digit determination result is notified to an external device.
Or the position measurement method according to 6. 8. The position measurement method according to claim 2, wherein the output of the bar code reader is not updated based on the check digit determination result.