JP2023104059A - Position identification device - Google Patents

Abstract

To provide a position identification device that can identify the self position of a moving body with high accuracy even if a detection omission of a magnetic marker occurs.SOLUTION: A position identification device 1 comprises: a table data memory unit 7 for memorizing positional information of multiple magnetic markers 3; a self-position estimation unit 11 for estimating the self position of a moving body 2; a marker searching unit 12 for searching a magnetic marker 3 closest to the self position of the moving body 2, which is estimated by the self-position estimation unit 11, from among the multiple magnetic markers 3 memorized by the table data memory unit 7 for a target magnetic marker 3; a magnetic sensor 6 for detecting the magnetic markers 3; a detection determination unit 13 for determining whether the target magnetic marker 3 is detected by the magnetic sensor 6; and a self-position determination unit 14 for determining the self position of the moving body 2 using the positional information of the target magnetic marker 3 when the target magnetic marker 3 is determined to be detected.SELECTED DRAWING: Figure 1

Description

The present invention relates to position determination devices.

As a conventional position specifying device, for example, the technology described in Patent Document 1 is known. The position specifying device described in Patent Document 1 specifies the position of the vehicle based on the position of the magnetic marker that serves as a reference when the vehicle moves within a travel area in which the magnetic markers are arranged. On the route after passing the marker, the position of the vehicle is specified using the number of passages of the magnetic marker.

JP 2020-17035 A

By the way, if some external factor such as an iron plate being placed on the magnetic marker occurs, the magnetic marker may not be detected by the magnetic sensor. However, in the conventional technology described above, the self-position of the vehicle is specified using the number of passages of the magnetic markers detected by the magnetic sensor. Therefore, if the magnetic sensor fails to detect the magnetic marker (missed detection of the magnetic marker), the vehicle may erroneously identify its own position.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a position specifying device capable of specifying the self-position of a mobile object with high accuracy even if detection omission of a magnetic marker occurs.

One aspect of the present invention is a position specifying device that specifies the position of a moving object when the moving object travels along a plurality of magnetic markers, the position specifying device comprising: a storage unit that stores position information of the plurality of magnetic markers; A self-position estimating unit for estimating the self-position of a moving object, and a magnetic marker closest to the self-position of the moving object estimated by the self-position estimating unit among a plurality of magnetic markers stored in a storage unit. a marker detection unit that detects the magnetic marker; a detection determination unit that determines whether the target magnetic marker searched by the marker search unit is detected by the marker detection unit; a self-position determination unit that determines the self-position of the moving body using the position information of the target magnetic marker stored in the storage unit when it is determined that the target magnetic marker has been detected.

In such a position specifying device, the self-position of the mobile body is estimated by the self-position estimator when the mobile body travels along the plurality of magnetic markers. Then, among the plurality of magnetic markers stored in the storage unit, the magnetic marker closest to the self-position of the moving body is searched as the target magnetic marker. Then, when it is determined that the target magnetic marker has been detected by the marker detection unit, the position information of the target magnetic marker is used to determine the self-position of the moving object. Therefore, even if a specific magnetic marker is not detected by the marker detection unit due to some external factor, the magnetic marker closest to the self-position of the moving body is searched again as the target magnetic marker. As a result, the self-position of the mobile body can be specified with high accuracy even if the detection omission of the magnetic marker occurs.

The marker detection unit is capable of detecting the amount of lateral displacement of the magnetic marker with respect to the center of the marker detection unit, and the self-position determination unit detects the position information of the target magnetic marker and the amount of lateral displacement of the target magnetic marker with respect to the center of the marker detection unit. You may determine the self-position of a mobile body based on. In such a configuration, when the moving body passes the target magnetic marker, the marker detection unit detects the lateral shift amount of the target magnetic marker with respect to the center of the target marker detection unit. Therefore, the self-position of the moving object is determined in consideration of the amount of lateral displacement of the target magnetic marker with respect to the center of the target marker detection unit. Therefore, the self-position of the mobile body can be identified with even higher accuracy.

The self-position estimation unit may estimate the self-position of the moving body using dead reckoning. A sensor for dead reckoning is often installed in a moving object such as a vehicle. In this case, since there is no need to separately prepare a sensor used for estimating the self-position of the mobile body, cost reduction can be achieved.

ADVANTAGE OF THE INVENTION According to this invention, even if detection omission of a magnetic marker occurs, the self-position of a mobile body can be pinpointed with high precision.

1 is a schematic block diagram of a locating device according to an embodiment of the present invention; FIG. FIG. 4 is a diagram showing an example of magnetic markers installed on a travel route together with a moving body; 3 is a table showing table data including position information of the magnetic markers shown in FIG. 2; 2 is a flow chart showing the procedure of arithmetic processing executed by the arithmetic processing unit shown in FIG. 1; 2 is a bottom view showing a state in which the magnetic sensor shown in FIG. 1 is mounted on a moving object; FIG. FIG. 4 is a diagram showing an example of a travel route along which a mobile body travels along magnetic markers; FIG. 7 is a diagram showing, as a comparative example, a state in which a moving body enters an incorrect route when there is an undetectable magnetic marker on the traveling route shown in FIG. 6; FIG. 7 is a diagram showing how the moving object accurately travels along the travel route shown in FIG. 6 even when there is an undetectable magnetic marker on the travel route.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic block diagram of a locating device according to one embodiment of the present invention. In FIG. 1, a position specifying device 1 of the present embodiment is provided in an automatic travel system that automatically travels a moving body 2 (see FIG. 2) such as a towing truck or a forklift to a destination. The automatic driving system is mounted on the mobile body 2 .

The moving body 2 has four wheels 2a, as shown in FIG. In addition, although not shown, the moving body 2 has, for example, a traveling motor that rotates driving wheels of the four wheels 2a and a steering motor that steers the steering wheels of the four wheels 2a. ing.

As shown in FIG. 2, the position specifying device 1 is a device that specifies the self-position of the mobile body 2 when the mobile body 2 travels along a plurality of magnetic markers 3 installed on a travel route R. . The magnetic markers 3 are embedded in the road surface or the floor surface of the travel route R at intervals. The shape of the magnetic marker 3 is, for example, rectangular. Also, the magnetic marker 3 may extend in the width direction of the travel route R (see FIGS. 6 to 8). The travel route R is set by an input device such as navigation.

The position specifying device 1 includes a wheel encoder 4 , a gyro sensor 5 , a magnetic sensor 6 , a table data storage section 7 and an arithmetic processing unit 8 .

The wheel encoder 4 is a sensor that detects the moving distance of the moving body 2 by measuring the rotation angle of the wheels 2 a of the moving body 2 . The gyro sensor 5 is a sensor that detects the orientation of the moving body 2 by measuring the angular velocity of the moving body 2 .

The wheel encoder 4 and the gyro sensor 5 are inertial sensors for dead reckoning. Dead reckoning is dead-reckoning in which movement information including the amount and direction of movement of a mobile object is acquired by an inertial sensor, and the self-position of the mobile object is estimated by cumulatively calculating the movement information.

The magnetic sensor 6 is a sensor (marker detector) that detects the magnetic marker 3 . The magnetic sensor 6 is attached to the bottom of the vehicle body 2b of the moving body 2 (see FIG. 5). As the magnetic sensor 6, for example, a highly sensitive micro magnetic sensor (MI sensor) is used. The magnetic sensor 6 detects the magnetic marker 3 by detecting magnetism existing within a predetermined range.

The magnetic sensor 6 extends in the vehicle width direction of the moving body 2 (see FIG. 5). Therefore, the detection range of the magnetic sensor 6 is widened in the vehicle width direction of the moving body 2 . Therefore, the magnetic sensor 6 can detect not only the magnetic marker 3 itself but also the amount of lateral displacement of the magnetic marker 3 with respect to the center G of the magnetic sensor 6 (described later).

The table data storage unit 7 is a storage unit that stores the position information of the plurality of magnetic markers 3 as table data, as shown in FIG. The position information of the magnetic marker 3 is represented by two-dimensional coordinates (XY coordinates).

The table data includes the marker ID of the magnetic marker 3, the X coordinate of the magnetic marker 3, and the Y coordinate of the magnetic marker 3. FIG. The table data storage unit 7 stores table data including marker IDs, X coordinates, and Y coordinates of the magnetic markers 3A to 3G shown in FIG.

The arithmetic processing unit 8 is composed of a CPU, a RAM, a ROM, an input/output interface, and the like. The arithmetic processing unit 8 has a self-position estimation section 11 , a marker search section 12 , a detection determination section 13 and a self-position determination section 14 .

The self-position estimator 11 estimates the current self-position of the mobile body 2 based on the moving distance of the mobile body 2 detected by the wheel encoder 4 and the orientation of the mobile body 2 detected by the gyro sensor 5 . That is, the self-position estimation unit 11 estimates the current self-position of the moving body 2 using dead reckoning.

The marker searching unit 12 selects the magnetic marker 3 closest to the self-position of the moving body 2 estimated by the self-position estimating unit 11 among the plurality of magnetic markers 3 stored in the table data storage unit 7 as the target magnetic marker 3 . explore as

The detection determination unit 13 determines whether or not the target magnetic marker 3 searched by the marker search unit 12 has been detected by the magnetic sensor 6 .

When the detection determination unit 13 determines that the target magnetic marker 3 has been detected, the self-position determination unit 14 uses the position information of the target magnetic marker 3 stored in the table data storage unit 7 to determine the position of the moving object. 2 determine the self-position. The self-position determination unit 14 determines the self-position of the moving body 2 based on the position information of the target magnetic marker 3 and the amount of lateral displacement of the target magnetic marker 3 with respect to the center G of the magnetic sensor 6 .

FIG. 4 is a flow chart showing the procedure of arithmetic processing executed by the arithmetic processing unit 8. As shown in FIG. This process is executed after the travel route R of the mobile object 2 is set until the mobile object 2 travels along the travel route R from the travel start position and reaches the destination.

In FIG. 4, the arithmetic processing unit 8 first acquires the detection values of the wheel encoder 4 and the gyro sensor 5 (step S101). Then, the arithmetic processing unit 8 estimates the current self-position of the moving body 2 based on the detection values of the wheel encoder 4 and the gyro sensor 5 (step S102).

Subsequently, the arithmetic processing unit 8 selects the magnetic marker 3 closest to the self-position of the moving body 2 (the closest magnetic marker to the self-position of the moving body 2) among the plurality of magnetic markers 3 stored in the table data storage unit 7. magnetic marker 3) is searched as the target magnetic marker 3 (step S103). For example, in the state shown in FIG. 2, the current self-position of the moving body 2 is X=9m, Y=-1m. Therefore, the magnetic marker 3B with the marker ID of 2 is searched for as the magnetic marker 3 closest to the self-position of the moving body 2 .

At this time, for example, among all the magnetic markers 3 included in the traveling route R of the moving body 2, the magnetic markers 3 excluding the magnetic markers 3 already detected by the magnetic sensor 6 are selected from among the plurality of magnetic markers 3. The magnetic marker 3 closest to the moving direction of the moving body 2 (including the front-rear direction of the moving body 2) from the position is searched as the magnetic marker 3 of interest. In this case, the magnetic markers 3 that are not included in the traveling route R of the mobile object 2 and the magnetic markers 3 that are arranged on the side of the mobile object 2 are not searched as target magnetic markers 3 .

Subsequently, the arithmetic processing unit 8 acquires the detection value of the magnetic sensor 6 (step S104). Then, the arithmetic processing unit 8 determines whether or not the target magnetic marker 3 is detected based on the detection value of the magnetic sensor 6 (step S105). When the arithmetic processing unit 8 determines that the target magnetic marker 3 is not detected, it executes the above step S101 again.

When the arithmetic processing unit 8 determines that the target magnetic marker 3 has been detected, the position information of the target magnetic marker 3 stored in the table data storage unit 7 and the target magnetic marker 3 with respect to the center G of the magnetic sensor 6 and the amount of lateral deviation of the moving body 2 (step S106).

The lateral displacement amount D of the magnetic marker 3 with respect to the center G of the magnetic sensor 6 is the distance from the center G of the magnetic sensor 6 to the center G0 of the magnetic marker 3, as shown in FIG. Note that the center G of the magnetic sensor 6 is the center of the magnetic sensor 6 in the vehicle width direction of the moving body 2 . The center G0 of the magnetic marker 3 is the center of the magnetic marker 3 in the vehicle width direction of the moving body 2 .

For example, as shown in FIG. 2, when the moving body 2 moves straight from the state where X=9 m and Y=-1 m, when the moving body 2 passes the magnetic marker 3B, the center G of the magnetic sensor 6 and the magnetic marker 3B, the self-position of the moving body 2 is determined to be X=10 m and Y=-1 m. If there is no lateral displacement between the center G of the magnetic sensor 6 and the magnetic marker 3B when the moving body 2 passes the magnetic marker 3B, the self-position of the moving body 2 will be the position of the magnetic marker 3B (X=10 m , Y=0m).

Subsequently, the arithmetic processing unit 8 updates the self-position of the mobile body 2 determined in step S106 as a new self-position of the mobile body 2 (step S107), and executes the above step S101 again.

Here, the self-position estimation unit 11 executes steps S101 and S102. The marker search unit 12 executes step S103. The detection determination unit 13 executes steps S104 and S105. The self-position determination unit 14 executes procedures S106 and S107.

In the position specifying device 1 as described above, dead reckoning using the wheel encoder 4 and the gyro sensor 5 sequentially estimates the self-position of the moving body 2 . However, dead reckoning alone tends to accumulate errors in self-position estimation. Therefore, by detecting the magnetic marker 3 embedded in the road surface or floor surface of the travel route R, the self-position of the moving body 2 is corrected. In this case, self-position estimation of the moving body 2 is performed between the magnetic markers 3 by dead reckoning.

For example, as shown in FIG. 6, when the travel route R to the destination is set by going straight, turning right, going straight, turning left, and going straight, the moving body 2 is set to the magnetic markers 3A to 3C, 3H to 3J. , 3N to 3Q in order to reach the destination. At this time, the magnetic markers 3A to 3C, 3H to 3J, and 3N to 3Q are sequentially detected by the magnetic sensor 6, so that the self-position of the moving body 2 is determined and updated.

By the way, for example, when the number of passages of the magnetic markers 3 and the order of the magnetic markers 3 are collated to specify the position of the moving body 2, the following problem occurs. For example, as shown in FIG. 7, when an iron plate is placed on the magnetic marker 3B, the magnetic sensor 6 cannot detect the magnetic marker 3B.

In this case, since the magnetic marker 3A is detected when the moving body 2 passes the first magnetic marker 3A, the position coordinates of the magnetic marker 3A are determined as the self-position of the moving body 2. FIG. Next, even if the moving body 2 passes the second magnetic marker 3B, the magnetic marker 3B cannot be detected. Therefore, the magnetic marker 3C is detected when the moving body 2 passes the third magnetic marker 3C. In other words, the magnetic sensor 6 skips reading (detection omission) of the second magnetic marker 3B. However, the arithmetic processing unit 8 recognizes the third magnetic marker 3C as the second magnetic marker 3B. Therefore, when the third magnetic marker 3C is detected, the position coordinates of the second magnetic marker 3B are determined as the self-position of the moving body 2. FIG.

Next, when the moving body 2 passes the fourth magnetic marker 3D, the magnetic marker 3D is detected, but the arithmetic processing unit 8 recognizes the fourth magnetic marker 3D as the third magnetic marker 3C. Therefore, the position coordinates of the third magnetic marker 3C are determined as the self-position of the moving body 2. FIG. The fourth magnetic marker 3D is not included in the travel route R that has been set. As a result, the moving body 2 enters the wrong route.

To address such a problem, in the present embodiment, the magnetic marker 3 closest to the self-position of the moving object 2 estimated by the self-position estimation unit 11 based on the detection value of the magnetic sensor 6 is selected as the target magnetic marker 3. to be explored. Then, when the target magnetic marker 3 is detected by the magnetic sensor 6 , the position information of the target magnetic marker 3 stored in the table data storage unit 7 is used to determine the self-position of the moving body 2 .

For example, as shown in FIG. 8, when the iron plate is placed on the magnetic marker 3B, the magnetic sensor 6 does not detect the magnetic marker 3B in the same manner as described above. However, when the mobile object 2 passes the magnetic marker 3B and approaches the next magnetic marker 3C, the self-position of the mobile object 2 estimated by the self-position estimation unit 11 among the plurality of magnetic markers 3 included in the travel route R The magnetic marker 3C is searched as the magnetic marker 3 closest to . Therefore, when the magnetic marker 3C is detected, the position coordinates of the magnetic marker 3C stored in the table data storage unit 7 are used to determine the self-position of the moving body 2. FIG. As a result, the moving body 2 is prevented from entering the wrong route, and the moving body 2 travels along the set travel route R to the destination.

As described above, according to this embodiment, the self-position of the mobile body 2 is estimated by the self-position estimation unit 11 when the mobile body 2 travels along the plurality of magnetic markers 3 . Then, among the plurality of magnetic markers 3 stored in the table data storage unit 7, the magnetic marker 3 closest to the self-position of the moving body 2 is searched as the target magnetic marker 3. FIG. Then, when it is determined that the target magnetic marker 3 has been detected by the magnetic sensor 6 , the position information of the target magnetic marker 3 is used to determine the self-position of the moving body 2 . Therefore, even if the specific magnetic marker 3 is not detected by the magnetic sensor 6 due to some external factor, the magnetic marker 3 closest to the self-position of the moving body 2 will be searched again as the target magnetic marker 3 . . As a result, even if the detection omission of the magnetic marker 3 occurs, the self-position of the moving body 2 can be specified with high accuracy.

Further, in this embodiment, when the moving body 2 passes the target magnetic marker 3 , the magnetic sensor 6 detects the lateral shift amount D of the target magnetic marker 3 with respect to the center G of the magnetic sensor 6 . Therefore, the self-position of the moving body 2 is determined in consideration of the amount of lateral displacement of the target magnetic marker 3 with respect to the center G of the magnetic sensor 6 . Therefore, the self-position of the moving body 2 can be identified with even higher accuracy.

Further, in the present embodiment, the self-position estimation unit 11 estimates the self-position of the moving body 2 using dead reckoning. Inertial sensors for dead reckoning are often installed in moving bodies such as vehicles. In this case, there is no need to separately prepare a sensor for estimating the self-position of the moving body 2, so cost reduction can be achieved.

In addition, this invention is not limited to the said embodiment. For example, in the above-described embodiment, the magnetic sensor 6 can detect the amount of lateral deviation D of the magnetic marker 3 with respect to the center G of the magnetic sensor 6, but it is not limited to this form, and the amount of lateral deviation D of the magnetic marker 3 cannot be detected. An inexpensive magnetic sensor may be used. In this case, when the magnetic marker 3 is detected by the magnetic sensor, the position information of the magnetic marker 3 stored in the table data storage unit 7 may be specified as the position of the moving body 2 .

In addition, in the above embodiment, the wheel encoder 4 and the gyro sensor 5 are used as inertial sensors for dead reckoning. ), etc. may be used.

In addition, in the above embodiment, the self-position estimating unit 11 estimates the self-position of the moving body 2 using dead reckoning, but it is not particularly limited to such a form. Self-position estimation techniques for estimating the self-position of the moving body 2 include, for example, a laser SLAM (Simultaneous Localization and Mapping) technique using detection data from a laser sensor, an image SLAM technique using camera image data, or an RTK- A GNSS (Real Time Kinematic-Global Navigation Satellite System) positioning method or the like may be used.

Further, the position specifying device 1 of the above embodiment is mounted on a vehicle such as a towing truck or a forklift, but the present invention can also be applied to a moving body such as a transport robot that travels along a plurality of magnetic markers. .

REFERENCE SIGNS LIST 1 position identifying device 2 moving object 3 magnetic marker 6 magnetic sensor (marker detection unit) 7 table data storage unit (storage unit) 11 self-position estimation unit 12 marker search unit Reference numerals 13: detection determination unit, 14: self-position determination unit, D: lateral displacement amount, G: center.

Claims (3)

A position specifying device for specifying the position of a moving object when the moving object travels along a plurality of magnetic markers,
a storage unit that stores position information of the plurality of magnetic markers;
a self-position estimation unit that estimates the self-position of the moving body;
a marker search unit that searches for a magnetic marker closest to the self-position of the moving body estimated by the self-position estimation unit, among the plurality of magnetic markers stored in the storage unit, as a target magnetic marker;
a marker detection unit that detects the magnetic marker;
a detection determination unit that determines whether the target magnetic marker searched by the marker search unit is detected by the marker detection unit;
self-position determining the self-position of the moving object using the position information of the target magnetic marker stored in the storage unit when the detection determination unit determines that the target magnetic marker is detected; and a determiner. The marker detection unit is capable of detecting a lateral displacement amount of the magnetic marker with respect to the center of the marker detection unit,
2. The self-position determination unit according to claim 1, wherein the self-position determination unit determines the self-position of the moving object based on the position information of the target magnetic marker and the amount of lateral displacement of the target magnetic marker with respect to the center of the marker detection unit. locating device. 3. The position specifying device according to claim 1, wherein the self-position estimator estimates the self-position of the mobile body using dead reckoning.

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