JP4379439B2 - Position detection system - Google Patents

Description

  The present invention relates to a position detection system, and more particularly to a system that accurately detects a current position using a simple sensor.

As a means for detecting the current position of a vehicle or the like, a method of receiving a radio wave signal from a GPS satellite by a receiver, a method of calculating a current position by detecting a moving distance and direction with a sensor, a barcode, an RFID There are various methods such as a method in which a landmark in which position information is written using characters or the like is placed on a passage and the position information is read from the landmark.
However, since it is necessary for GPS to capture radio signals with a receiver, it cannot be used indoors where radio signals from GPS satellites do not reach.
In addition, the method of calculating the current position from the movement distance and azimuth has a problem that accurate position detection is difficult because an error occurs in the movement distance and azimuth detected by the sensor.
Further, in the method of reading the position information from the landmark on the passage, the position information reading device composed of precision equipment such as a bar code reader, RFID reader, and character recognition device is expensive, and this position information reading device is used for traveling of the vehicle or the like. It is necessary to devise a mounting design that can withstand the vibrations involved.

  Therefore, in the position information providing method disclosed in Patent Document 1, magnetic marks including any one of the S and N poles of the permanent magnet and the nonmagnetic material are arranged in two rows on the path, and these two rows of magnetism are arranged. Two magnetic sensors corresponding to the mark are mounted on the vehicle, and when the detection value of one magnetic sensor changes as the vehicle advances, the detection value of the other magnetic sensor is read. The current position is obtained by an information code by combination.

JP 7-244526 A

  In the method of Patent Document 1, it is possible to detect the position using an inexpensive and simple magnetic sensor, but in order to obtain an information code based on a combination of detected values of the magnetic mark, the magnetic marks arranged in two rows It is necessary to read the detected value of the magnetic mark while moving the vehicle along the line. Therefore, if there is no past position information (magnetic mark detection value) up to the current position, the current position cannot be grasped only by being positioned on the path where the magnetic marks are arranged. In addition, for example, even when a vehicle enters from the side with respect to the path in which the magnetic marks are arranged, an accurate current position cannot be obtained.

  The present invention has been made to solve such problems, and it is possible to accurately detect the current position using a simple sensor without being limited by the presence or absence of position information and the traveling direction up to the current position. It is an object of the present invention to provide a position detection system that can be used.

  The position detection system according to the present invention is a system for detecting the current position of a moving body that moves on a floor surface, each of which has binary data and is arranged on the floor surface according to a predetermined two-dimensional pattern. Binary marks and binary data of binary marks on the floor surface that are mounted on the moving body in a predetermined sensor array pattern having the same pitch as the array pitch of the binary marks substantially parallel to the floor surface A combination of binary data of binary marks existing in a predetermined sensor array pattern when a predetermined sensor array pattern of a moving body is superimposed at an arbitrary position on a predetermined two-dimensional pattern Binary data of binary marks read by each of a plurality of reading sensors and a positional information storage device that associates the pattern with the position of the moving body at that time From the position information storage device based on a combination pattern is obtained by an arithmetic unit for obtaining a current position of the moving body. The predetermined two-dimensional pattern in which the binary marks are arranged is a pattern in which a binary number sequence of a linear maximum periodic sequence corresponding to the number of reading sensors is arranged on a two-dimensional plane.

An azimuth angle sensor for detecting the azimuth angle of the moving body is further mounted on the moving body, and the arithmetic device combines the azimuth angle detected by the azimuth sensor and the binary data of the binary mark read by each of the plurality of reading sensors. You may comprise so that the present position of a mobile body may be determined based on a pattern.
For example, binary marks can be arranged in 4 rows and 6 columns as a predetermined two-dimensional pattern, and four reading sensors can be arranged in a rectangular shape as a predetermined sensor arrangement pattern.
Note that a binary mark can be formed from a magnetic material having two polarities of S pole and N pole as binary data, and the magnetic sensor can be used as a reading sensor. Alternatively, a binary mark having two kinds of colors as binary data can be used, and a color sensor can be used as a reading sensor.

  According to the present invention, since the current position of the mobile body is obtained based on the binary data combination pattern of the binary marks on the floor surface existing in the predetermined sensor arrangement pattern, the position information up to the current position can be obtained. The present position can be accurately detected using a simple sensor without being limited by the presence or absence or the traveling direction.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1
The position detection system of the present invention is applied to a load transport system using a cargo handling vehicle such as a forklift. As shown in FIG. 1, a forklift 1 as a moving body has a fork 3 that can be raised and lowered at the front part of a machine base 2, and a load detection sensor 4 that is attached to the lower part of the front end of the machine base 2 facing forward. have. The load detection sensor 4 detects that a load has been placed in front of the machine base 2 by the fork 3.
Further, four magnetic sensors 5 to 8 are mounted on the bottom of the machine base 2 in a rectangular sensor arrangement pattern substantially parallel to the floor surface on which the forklift 1 travels. The magnetic sensor 5 is arranged at the left front part of the machine base 2, the magnetic sensor 6 is arranged at the right front part of the machine base 2, the magnetic sensor 7 is arranged at the left rear part of the machine base 2, and the magnetic sensor 8 is arranged at the right rear part of the machine base 2. The machine base 2 is arranged with a pitch Lx in the width direction and with a pitch Ly in the front-rear direction. These magnetic sensors 5 to 8 are reading sensors for reading the polarity of a magnetic tape described later disposed on the floor surface.
Further, a control device 9 for obtaining position information of the forklift 1 based on detection signals from the magnetic sensors 5 to 8 is mounted on the machine base 2. As shown in FIG. 2, the control device 9 includes an arithmetic device 10 electrically connected to the load detection sensor 4 and the magnetic sensors 5 to 8, and a position information storage device 11 connected to the arithmetic device 10. Have.

Here, a load conveying system using the forklift 1 will be described. As shown in FIG. 3, a loading area 12 is set on the floor of a warehouse or the like, and the arrangement in the loading area 12 is set as “row” in FIG. 3 and “column” in the Y direction. In addition, six loading positions S1 to S6 are partitioned in a pattern of 2 rows and 3 columns.
An operator places the load W on the fork 3 of the forklift 1 and travels on the floor, and places the load W at a specified loading position in the loading area 12, for example, the loading position S1. At this time, it is necessary to position the machine base 2 of the forklift 1 just before the loading position S1 so that the load W on the fork 3 is positioned immediately above the loading position S1.

  Therefore, as shown in FIG. 4, a magnetic area 13 in which a large number of magnetic bodies M are arranged in a predetermined two-dimensional pattern is formed on the floor surface in front of the loading positions S1 to S3. In the magnetic area 13, 24 magnetic bodies M are arranged in a pattern of 4 rows and 6 columns with a pitch Lx in the X direction and a pitch Ly in the Y direction. That is, the magnetic bodies M are arranged at the same pitch as the arrangement pitch of the magnetic sensors 5 to 8 of the forklift 1.

Further, the six loading positions S1 to S6 in the loading area 12 are arranged with a pitch 2 · Lx in the X direction and with a pitch 2 · Ly in the Y direction. That is, the loading positions S <b> 1 to S <b> 6 are arranged at a pitch twice the arrangement pitch of the magnetic sensors 5 to 8 of the forklift 1 and the 24 magnetic bodies M in the magnetic area 13. Then, twelve magnetic bodies M in the first and second rows in the + Y direction in the four rows of arrangement patterns of the magnetic area 13 are arranged so as to overlap the loading positions S4 to S6 of the loading area 12. Yes.
Each magnetic body M constitutes the binary mark of the present invention, and is made of a thin magnetic tape, and is affixed on the floor surface as binary data with the north or south pole facing upward.

  As shown in FIG. 5, for example, when the machine base 2 of the forklift 1 enters the magnetic area 13 to place the load W at the loading position S <b> 1 in the loading area 12, the magnetic sensors 5 to 8 of the forklift 1 are moved. Since the arrangement pitch and the arrangement pitch of the magnetic bodies M are equal, the four magnetic sensors 5 to 8 arranged in a rectangular sensor arrangement pattern on the bottom of the machine base 2 are used to select the 24 magnetic bodies M in the magnetic area 13. The polarities of the four magnetic bodies M are detected. In the example of FIG. 5, the magnetic sensor 5 to 8 can obtain a combination pattern of “N, S, S, N” polarities. At this time, if the position of the forklift 1 changes, the four magnetic bodies M selected according to the position also change. However, as shown in FIG. 6, any four magnets in the magnetic area 13 are changed. Even when the body M is selected, 24 magnetic bodies M are arranged so that their combination patterns of polarities are all different.

  That is, when 24 magnetic bodies M arranged in 4 rows and 6 columns are selected from four magnetic bodies M in a rectangular sensor arrangement pattern as depicted by a thick line in FIG. 6, a total of 15 selections are made. Although possible, they have combination patterns P1 to P15 having polarities that are all different from each other.

A method of forming the magnetic area 13 having 15 kinds of combination patterns P1 to P15 will be described. First, a binary number sequence of “0” and “1” of the linear maximum periodic sequence (M series) corresponding to the number “4” of the magnetic sensors 5 to 8 of the forklift 1 is formed. Here, the linear maximum periodic sequence is a 1-bit number sequence generated by the following linear recurrence formula (1).
_Xn = _Xnp + _Xnq (p> q) (1)
Note that n is an integer, and “+” indicates exclusive OR. Further, the number “4” of the magnetic sensors 5 to 8 is used as p, and q is selected so that the following equation (2) becomes an irreducible polynomial, and “1” is selected here.
X ^p + X ^q +1 (2)
If, for example, X ₀ = X ₁ = X ₂ = X ₃ = 1 is given as an initial value, a linear maximum periodic sequence having a period “15” shown in Table 1 below is obtained from Equation (1).

  Next, as shown in FIG. 7A, the upper left first row, the first column square to the second row, the second row square in the 3 rows and 5 columns squares to represent 15 patterns, Furthermore, the ranking is given as “1, 2, 3” diagonally to the lower right, such as a cell in the third row and the third column. When it reaches the third row, it returns to the first row, and when it reaches the fifth column, it returns to the first column as shown in FIG. As shown in c), ranks from “1” to “15” are assigned to the 15 cells.

Substituting the 15 number sequences _Xn shown in Table 1 into squares according to this order, a binary array pattern of “0” and “1” as shown in FIG. 8A is formed. The first row of this array pattern is copied as it is to the fourth row to form a 4-row, 5-column array pattern as shown in FIG. 8B, and the first column is copied as it is to the sixth column. An array pattern of 4 rows and 6 columns as shown in FIG. 8C is formed.
Then, by applying the S pole as “0” and the N pole as “1” in the array pattern of 4 rows and 6 columns, the magnetic area 13 composed of the 24 magnetic bodies M shown in FIG. 4 is obtained.

  Table 2 shows the polarities detected by the magnetic sensors 5 to 8 for the 15 combination patterns P1 to P15 shown in FIG.

  In Table 2, the “decimal number” column at the right end indicates the binary number obtained by sequentially arranging the polarities detected by the magnetic sensors 5 to 8 with the S pole being “0” and the N pole being “1”. The value converted to a hexadecimal number. The fifteen combination patterns P1 to P15 have different values from “1” to “15” when expressed in decimal numbers.

  The decimal numbers corresponding to the combination patterns P1 to P15 shown in Table 2 and the positions of the rectangular sensor arrangement patterns in the magnetic area 13 corresponding to the combination patterns P1 to P15 shown by thick lines in FIG. 1 is stored in advance in the position information storage device 11 of the control device 9 mounted on the control device 9.

  Next, the operation of the position detection system according to the first embodiment will be described. It is assumed that the operator transports the load W with the forklift 1 and places the load W at the specified load storage position S1 in the load storage area 12. As shown in FIG. 5, the operator places the machine base 2 of the forklift 1 at the loading position so that the load W on the fork 3 is located immediately above the loading position S1 with the forklift 1 facing the + Y direction. Stop before S1.

  Here, when the fork 3 is lowered and the load W is placed at the load storage position S1, the load detection sensor 4 attached to the lower part of the front end of the machine base 2 detects that the load W has been placed. Using the detection signal from the sensor 4 as a trigger, the magnetism of the magnetic area 13 on the floor surface detected by each of the four magnetic sensors 5 to 8 arranged at the bottom of the machine base 2 by the arithmetic device 10 in the control device 9. The polarity of the body M is read. In this case, as shown in FIG. 5, polarities of “N”, “S”, “S”, and “N” are obtained by the magnetic sensors 5 to 8, respectively, and the arithmetic unit 10 sets the S pole to “0”. , N pole is set to “1” to form a binary number “1001” in which these polarity combination patterns “N, S, S, N” are sequentially arranged, and this is converted into a decimal number to obtain the value “9”. obtain.

  The position of the rectangular sensor array pattern corresponding to this value “9” is read from the position information storage device 11. That is, the combination pattern P1 is extracted from Table 2, and the position indicated by the thick line in the combination pattern P1 in FIG. 6 is recognized. Since the rectangular sensor arrangement pattern is formed by the magnetic sensors 5 to 8 arranged at the bottom of the machine base 2 of the forklift 1, the position of the rectangular sensor arrangement pattern represents the position of the machine base 2 of the forklift 1. It will be. From the position of the machine base 2, it can be understood that the position where the fork 3 is lowered and the load W is placed is the load placement position S1. Therefore, the calculation device 10 can store the position on which the load W is placed, or can be transmitted to and stored in a management device (not shown) of the transport system by communication.

  Similarly, in FIG. 5, when the load W is placed at the loading position S2, the polarities “S”, “N”, and “N” of the four magnetic bodies M arranged in front of the loading position S2. , “S” is detected by the magnetic sensors 5 to 8, the decimal number “6” is obtained from the binary number “0110”, and it is determined from Table 2 that the combination pattern P 7. Therefore, the position indicated by the thick line in the combination pattern P7 in FIG. 6 is recognized, and it is understood that the position where the load W is placed is the load placement position S2.

  The magnetic sensors 5 to 8 used in the first embodiment have a simple structure, unlike a reading device composed of a precision device such as a bar code reader, an RFID reader, or a character recognition device. There is no need to devise a mounting design that can withstand the vibrations involved.

  In addition, although the thin magnetic tape was stuck on the floor as the magnetic body M which comprises a binary mark, it is not limited to the shape of magnetic bodies, such as plate shape and rod shape. However, when the magnetic body has a certain thickness, it is desirable to embed the magnetic body in the floor so that the surface of the magnetic body is substantially flush with the floor so as not to prevent the forklift 1 from traveling. .

Embodiment 2
The above-described polarity combination patterns by the four magnetic sensors 5 to 8 are formed by arranging the detected polarities in the order of the magnetic sensors 5 to 8, so that the rectangular sensor arrangement pattern of the forklift 1 is the magnetic area 13. However, if the direction of the forklift 1 changes even if it is in the same position, the magnetic bodies M corresponding to the magnetic sensors 5 to 8 will be different, and different combination patterns will be formed. For example, for the combination pattern P4 in FIG. 6, the magnetic sensors 5 to 8 detect “S”, “S”, “N”, and “N”, respectively, and the binary number “0011” to the decimal number “3”. However, if the direction of the forklift 1 is reversed at the same position, the magnetic sensors 5 to 8 detect “N”, “N”, “S”, and “S”, respectively, and the binary number “ The decimal number “12” is obtained from “1100”. Thereby, it is determined as a combination pattern P6 from Table 2, and there is a possibility that an incorrect position is grasped.

  Therefore, in the second embodiment, as shown in FIG. 9, the azimuth angle sensor 14 is mounted on the forklift 1, and the azimuth angle sensor 14 is electrically connected to the arithmetic device 10. The arithmetic unit 10 recognizes the azimuth angle of the forklift 1 based on the detection signal from the azimuth angle sensor 14, and combines the azimuth angle and the polarity combination patterns read by the four magnetic sensors 5 to 8 of the forklift 1. Based on this, the current position of the forklift 1 is calculated.

  For example, in FIG. 5, when the forklift 1 is directed in the −Y direction, the magnetic sensors 8, 7 are disposed at the positions where the magnetic sensors 5, 6, 7, and 8 are disposed when the forklift 1 is directed in the + Y direction, respectively. , 6 and 5 will be located. Therefore, when the azimuth sensor 14 detects that the forklift 1 is in the −Y direction, the arithmetic unit 10 determines the four polarities detected by the magnetic sensors 5 to 8 as the magnetic sensors 8, 7, 6 and 5. The combination pattern is extracted using Table 2.

  When the arrangement pitch Lx in the X direction and the arrangement pitch Ly in the Y direction of the magnetic sensors 5 to 8 of the forklift 1 and the 24 magnetic bodies M in the magnetic area 13 are substantially equal to each other, the forklift 1 is in the + X direction or −X. Similarly, when facing the direction, the azimuth angle sensor 14 detects the azimuth angle of the forklift 1, and the azimuth angle and the polar combination patterns read by the four magnetic sensors 5 to 8 of the forklift 1 are used. Based on this, the current position of the forklift 1 can be calculated.

Embodiment 3
In the first and second embodiments described above, the magnetic body M having binary data of the N pole and the S pole is used as the binary mark. However, in the third embodiment, as shown in FIG. 24 color bodies C having the two colors as binary data are arranged in a predetermined two-dimensional pattern on the floor surface in front of the loading positions S1 to S3, whereby a color area 23 is formed. The four color sensors 15 to 18 are mounted on the bottom of the machine base 2 of the forklift 1 in a rectangular sensor arrangement pattern substantially parallel to the floor on which the forklift 1 travels.

The predetermined two-dimensional pattern in which the colored body C is arranged is the same as the arrangement pattern of the magnetic body M in the first and second embodiments. For example, the red color of the colored body C is used instead of the N pole of the magnetic body M. Instead of the south pole of the magnetic body M, the white color of the colored body C is arranged.
By recognizing the color of the colored body C with the color sensors 15 to 18 of the forklift 1, the same effects as those of the first and second embodiments can be obtained.

Similarly to the magnetic sensors 5 to 8 in the first and second embodiments, the color sensors 15 to 18 used in the third embodiment are also reading devices including precision devices such as a barcode reader, an RFID reader, and a character recognition device. Since the structure is simple unlike the above, it is not necessary to devise a mounting design that can withstand the vibration accompanying the traveling of the forklift 1.
The color of the colored body C is not limited to red and white, and two colors that can be recognized by the color sensors 15 to 18 may be freely selected.
As the colored body C, a thin colored tape can be affixed on the floor surface, or can be colored directly with paint or the like on the floor surface.
Further, as long as the binary data can be identified by the sensor mounted on the forklift 1, not only the magnetic body M and the colored body C but also other binary marks can be used.

In the above-described first to third embodiments, four reading sensors including the magnetic sensors 5 to 8 or the color sensors 15 to 18 are mounted on the forklift 1, and 24 binary signals including the magnetic body M or the colored body C are provided. The marks are arranged in 4 rows and 6 columns to form 15 combination patterns P1 to P15. However, the present invention is not limited to this. For example, when six reading sensors are used, 63 combinations of patterns can be formed by obtaining the linear maximum periodic sequence having the period “63” by setting the value of p in the above formula (1) to “6”. it can. Similarly, 255 combination patterns can be formed by using eight reading sensors, and 1023 combination patterns can be formed by using ten reading sensors.
In this way, by increasing the number of reading sensors mounted on the forklift 1, the number of combination patterns increases, and position detection can be performed within such a wide area. However, it is necessary to increase the number of binary marks arranged on the floor as the number of combination patterns increases.

  In each of the above-described embodiments, the example in which the position detection system is applied to the transport system using the forklift 1 has been described. However, the present invention is not limited to this, and the present invention is widely applied to detection of the current positions of various moving objects. be able to.

It is a top view which shows roughly the forklift used with the conveyance system to which the position detection system which concerns on Embodiment 1 of this invention was applied. It is a block diagram which shows the mounting apparatus of a forklift. It is a top view which shows the operation | movement at the time of mounting a load in a loading position with a forklift. It is a top view which shows the load storage area and magnetic area on a floor surface. It is a top view which shows the relationship between the magnetic sensor and magnetic area of a forklift at the time of mounting a load in a loading position. It is a figure which shows the combination pattern of the polarity of the magnetic body detected by four magnetic sensors, when a rectangular sensor arrangement pattern is piled up on a magnetic area. It is a figure which shows the method of forming the magnetic area of a predetermined two-dimensional pattern in order of a process. It is a figure which shows the method of forming the magnetic area of a predetermined two-dimensional pattern in order of a process. It is a block diagram which shows the mounting apparatus of the forklift used with the conveyance system to which the position detection system which concerns on Embodiment 2 was applied. It is a top view which shows the relationship between the color sensor of a forklift and a color area at the time of mounting a load in a loading position with the conveyance system to which the position detection system which concerns on Embodiment 3 was applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Forklift, 2 Machine stand, 3 Fork, 4 Load detection sensor, 5-8 Magnetic sensor, 9 Control apparatus, 10 Calculation apparatus, 11 Position information storage device, 12 Loading area, 13 Magnetic area, 14 Azimuth angle sensor, 15 -18 color sensor, 23 color area, Lx, Ly arrangement pitch, W load, S1-S6 loading position, M magnetic body, C colored body.

Claims (5)

A system for detecting a current position of a moving object moving on a floor surface,
A number of binary marks each having binary data and arranged on the floor according to a predetermined two-dimensional pattern;
A plurality of binary data read from the binary marks on the floor surface mounted on the movable body and having a predetermined sensor arrangement pattern having the same pitch as the arrangement pitch of the binary marks substantially parallel to the floor surface. A reading sensor,
A combination pattern of binary data of the binary marks existing in the predetermined sensor array pattern when the predetermined sensor array pattern of the movable body is overlaid at an arbitrary position on the predetermined two-dimensional pattern, and A position information storage device for associating the position of the mobile object with
An arithmetic unit that obtains a current position of the moving body from the position information storage device based on a combination pattern of binary data of the binary marks read by the plurality of reading sensors, and the predetermined two-dimensional pattern Is a pattern in which binary sequences of linear maximum periodic sequences corresponding to the number of reading sensors are arranged in a two-dimensional plane. An azimuth angle sensor mounted on the movable body and detecting an azimuth angle of the movable body;
The arithmetic unit determines a current position of the moving body based on an azimuth angle detected by the azimuth sensor and a combination pattern of binary data of the binary mark read by the plurality of reading sensors. Item 2. The position detection system according to Item 1.   The position detection system according to claim 1 or 2, wherein the binary marks are arranged in 4 rows and 6 columns as the predetermined two-dimensional pattern, and the four reading sensors are arranged in a rectangular shape as the predetermined sensor arrangement pattern. .   The position detection according to claim 1, wherein the binary mark is made of a magnetic material having two polarities of S pole and N pole as binary data, and the reading sensor is made of a magnetic sensor. system.   The position detection system according to claim 1, wherein the binary mark has two colors as binary data, and the reading sensor is a color sensor.

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