WO2023243617A1

WO2023243617A1 - Magnetic marker, vehicular system, and marker detection method

Info

Publication number: WO2023243617A1
Application number: PCT/JP2023/021800
Authority: WO
Inventors: 孝幸安藤; 知彦長尾; 道治山本; 一雄浦川; 哲矢岩瀬; 潤中村
Original assignee: 愛知製鋼株式会社
Priority date: 2022-06-14
Filing date: 2023-06-12
Publication date: 2023-12-21

Abstract

This magnetic marker (10), which is disposed at distance along a travel path (1R) so as to be detectable during a movement of a vehicle, is a multiple-pole magnetic marker (10B) which is one magnetic marker composed of a plurality of magnet pieces (100) which are arranged so as to have magnetic polarities alternately different from each other. The multiple-pole magnetic marker (10B) can be detected with high reliability by detecting, on the vehicle side, a magnetism change which periodically and repetitively changes, the number of times of the periodic repetition corresponding to the number of the plurality of magnet pieces (100).

Description

Magnetic marker, vehicle system and marker detection method

The present invention relates to a magnetic marker detected while a vehicle is moving, a vehicle system including the magnetic marker, and a marker detection method for detecting the magnetic marker.

Conventionally, vehicles such as automatic guided vehicles have been widely used in facilities such as factories and distribution warehouses. BACKGROUND ART As a system for automatically driving a vehicle such as an automatic guided vehicle, a system that uses magnetic markers arranged along a travel route of the vehicle is known (for example, see Patent Document 1). In this system, a lateral deviation, which is the amount of lateral deviation of the vehicle with respect to a magnetic marker, is detected, and the vehicle is steered to suppress this deviation.

Additionally, systems to support vehicle driving, including automatic driving, have been proposed. As such a system, a system in which magnetic markers are installed along the lane in which a vehicle travels is known (for example, see Patent Document 2). In this system, for example, by detecting the amount of lateral deviation of the vehicle with respect to the magnetic marker, a lane departure warning is realized.

Japanese Patent Application Publication No. 2011-008598 Japanese Patent Application Publication No. 2018-165856

However, the conventional system has the following problems. In other words, steel footboards for workers installed on the floors of facilities such as factories and distribution warehouses, as well as reinforced concrete bridges and tunnels that make up the roads on which vehicles travel, contain iron, which is a magnetic material. There is a possibility that the magnetic field may become a magnetic source, and it may be difficult for the vehicle to distinguish between the magnetism acting on the magnetic marker and the magnetism acting from a magnetic generating source other than the magnetic marker.

The present invention has been made in view of the above conventional problems, and provides a magnetic marker that can be detected with high reliability, a vehicle system that can detect a magnetic marker with high reliability, and a marker that can detect a magnetic marker with high reliability. This paper attempts to provide a detection method.

One aspect of the present invention is a vehicle system in which magnetic markers are arranged at intervals on a vehicle running track,
The magnetic markers include at least a multipolar magnetic marker, which is a magnetic marker composed of a plurality of magnets arranged so that the magnetic polarities detected on the vehicle side are alternately different,
The vehicle has a detection processing circuit that executes processing for detecting the magnetic marker,
The detection processing circuit is capable of executing a multipolar magnetic marker detection process in which it is determined that one of the multipolar magnetic markers has been detected when a magnetic change that periodically changes repeatedly can be detected. It's in the system.

One aspect of the present invention is a marker detection method for detecting magnetic markers by a vehicle running on a track where magnetic markers are arranged at intervals, the method comprising:
The magnetic markers include at least a multipolar magnetic marker, which is a magnetic marker composed of a plurality of magnets arranged so that the magnetic polarities detected on the vehicle side are alternately different,
including a detection process for detecting the magnetic marker,
The detection process includes at least a multipolar magnetic marker detection process of determining that one magnetic marker that is the multipolar magnetic marker has been detected when a periodically repeating magnetic change can be detected. It's in the detection method.

One aspect of the present invention is a magnetic marker arranged at intervals along a running track so as to be detectable while a vehicle is moving, the magnetic marker comprising:
The magnetic marker is a multipolar magnetic marker that is a single magnetic marker composed of a plurality of magnets arranged so that the magnetic polarity is alternately different,
The magnetic marker is configured to be detectable by detecting periodically and repeatedly changing magnetic changes on the vehicle side.

One of the technical features of the present invention is a multipolar magnetic marker, which is a magnetic marker composed of a plurality of magnets arranged so that their magnetic polarities are alternately different. The multipolar magnetic marker applies periodically and repeatedly changing magnetic changes to the vehicle side. Such regular magnetic changes are relatively easy to distinguish from magnetic changes acting from a magnetic source that is a disturbance. On the vehicle side, by detecting such regular magnetic changes, multipolar magnetic markers can be detected with high reliability.

An explanatory diagram of a vehicle system. Diagram showing a monopolar magnetic marker. A diagram showing a multipolar magnetic marker. An explanatory diagram of a vehicle. A configuration diagram of a magnetic sensor array. FIG. 2 is a system diagram showing the system configuration of the towing vehicle. FIG. 3 is a flow diagram showing the flow of processing for detecting a magnetic marker. FIG. 4 is an explanatory diagram of magnetic changes exerted on a vehicle by a unipolar magnetic marker. FIG. 3 is an explanatory diagram of magnetic changes caused by a multipolar magnetic marker on a vehicle. FIG. 2 is an explanatory diagram of a magnetic change (second order difference) caused by a unipolar magnetic marker on a vehicle. FIG. 3 is a diagram illustrating a magnetic distribution curve in the vehicle width direction. An explanatory diagram of a magnetic distribution curve (first floor difference) in the vehicle width direction. FIG. 3 is an explanatory diagram of magnetic change (second order difference) that a multipolar magnetic marker acts on a vehicle. FIG. 3 is an explanatory diagram of direction detection processing using a multipolar magnetic marker. FIG. 3 is a diagram illustrating a tape-shaped multipolar magnetic marker. FIG. 3 is a diagram illustrating a sheet-like multipolar magnetic marker.

Embodiments of the present invention will be specifically described using the following examples.
(Example 1)
This example relates to a vehicle system 1 for a vehicle 2 to automatically travel along a predetermined route. This content will be explained using FIGS. 1 to 16.

The vehicle system 1 (FIG. 1) of this example is a system for facilities such as factories and warehouses. In the vehicle system 1, magnetic markers 10 are arranged at intervals (for example, 2 m) along a preset route 1R (an example of a running route). In the vehicle system 1, the vehicle 2 automatically travels while detecting the magnetic marker 10.

The vehicle system 1 of this example is also applicable to factories, warehouses, etc. where laying grooves (not shown) for laying electric wires are provided on the floor surface. The opening of the laying groove is covered with an iron footboard 19 that can serve as a source of magnetism. The route 1R is set to cross this footboard 19. In the vehicle system 1 of this example, through technical ingenuity, it is possible to detect the magnetic marker 10 with high reliability while suppressing false detection of magnetic sources that cause disturbance, such as the footboard 19 made of iron, which is a magnetic material. .

In the vehicle system 1 of this example, two types of magnetic markers 10 are used. The first magnetic marker 10 is a unipolar magnetic marker 10A (FIG. 2) made of a single piece-shaped magnet piece 100. The second magnetic marker 10 is a multipolar magnetic marker 10B (FIG. 3), which is a magnetic marker in which six magnet pieces 100 are linearly arranged so that the magnetic polarities are alternately different. In the vehicle system 1, one of the magnetic markers 10, either the multipolar magnetic marker 10B or the unipolar magnetic marker 10A, is arranged at 2 m intervals along the route 1R. Note that the multipolar magnetic marker 10B has a range along the direction of the route 1R. The distance of 2 m between the multipolar magnetic marker 10B and the adjacent magnetic marker 10 is set with reference to one representative magnet piece 100 among the six magnet pieces 100 constituting the multipolar magnetic marker 10B.

The six magnet pieces 100 constituting the multipolar magnetic marker 10B are arranged on a straight line along the direction of the route 1R. When the route 1R is a straight route, the arrangement direction of the six magnet pieces 100 matches the direction of the route 1R. When the route 1R is a curved road, the direction in which the six magnet pieces 100 are arranged coincides with the tangential direction of the curve formed by the route 1R. When the route 1R is a straight line, the direction of the straight line is the direction of the route 1R. When the route 1R is a curve, the tangential direction is the direction of the route 1R.

The magnet piece 100, which is an example of a magnet, is common to both the unipolar magnetic marker 10A and the multipolar magnetic marker 10B. The magnet piece 100 is a ferrite rubber magnet in which magnetic powder of iron oxide, which is a magnetic material, is dispersed in a polymer material, which is a base material. The shape of the magnet piece 100 is a sheet with a diameter of 50 mm and a thickness of 2 mm. The magnet piece 100 is a permanent magnet with one surface serving as a north pole and the other surface serving as a south pole.

The magnetic polarity detected on the vehicle 2 side changes depending on which surface of the magnet piece 100 is installed facing upward. Hereinafter, the magnetic polarity detected on the vehicle 2 side will be defined as the magnetic polarity of the magnet piece 100. In the following description and in FIGS. 2, 3, etc., the N-pole magnet piece 100 is referred to as a magnet piece 100N, and the S-pole magnet piece 100 is referred to as a magnet piece 100S.

The magnet piece 100 forming the unipolar magnetic marker 10A is a magnet piece 100N whose magnetic polarity detectable on the vehicle 2 side is north pole. In the multipolar magnetic marker 10B, the leading magnet piece 100, which is located on the upstream side of the route 1R and through which the vehicle 2 passes first, is an S-pole magnet piece 100S, and the rear end magnet piece 100 is an N-pole magnet piece. It is 100N.

The unipolar magnetic marker 10A and the multipolar magnetic marker 10B are used depending on the magnetic environment of the installation location. For example, the multipolar magnetic marker 10B is applied to installation locations where there is a magnetic source that causes disturbance, such as on or near a footboard 19 made of iron (see Figure 1), which is a magnetic material, and where the disturbance magnetic field is large. Ru. On the other hand, the unipolar magnetic marker 10A is applied to an installation location where there is no magnetic disturbance source nearby and the disturbance magnetic field is small. Note that it is also possible to actually measure the magnitude (intensity) of the disturbance magnetism at each installation location and use the multipolar magnetic marker 10B and the unipolar magnetic marker 10A depending on the measured result. For example, it is preferable to arrange the multipolar magnetic marker 10B at the installation location where disturbance magnetism exceeding a threshold value acts, and to arrange the unipolar magnetic marker 10A at the installation location where the disturbance magnetism is below the threshold value.

Next, the vehicle 2 that constitutes the vehicle system 1 of this example will be explained. As shown in FIG. 4, the vehicle 2 includes a towing vehicle 21 having drive wheels, and a four-wheeled cart 23 towed by the towing vehicle 21. The towing vehicle 21 has a length of 2 m and a width of 1 m, and the truck 23 has a length of 2 m and a width of 1 m.

The truck 23 is equipped with a connection bar 230 for connecting to the towing vehicle 21 or the preceding truck 23. The trolley 23 includes a pair of left and right front driven wheels 231 and a left and right pair of rear fixed wheels 232.

The towing vehicle 21 is a three-wheeled vehicle that includes one front wheel 211 that is a steered wheel and a pair of left and right rear wheels 212 that are drive wheels. In the towing vehicle 21 , a magnetic sensor array 3 is disposed in front of the front wheels 211 . The rod-shaped magnetic sensor array 3 is attached along the vehicle width direction of the towing vehicle 21.

The magnetic sensor array 3 (FIG. 5) is a rod-shaped unit in which a plurality of magnetic sensors Cn are arranged in a straight line, and is attached along the vehicle width direction of the towing vehicle 21 (see FIG. 4). In the configuration of this example, the magnetic sensor array 3 is attached to the front side of the front wheel 211. Note that the mounting height of the magnetic sensor array 3 with respect to the floor surface on which the vehicle 2 moves is 100 mm. The mounting position of the magnetic sensor array 3 may be at the rear of the vehicle body instead of the position in this example.

The magnetic sensor array 3 (FIG. 5) includes 15 magnetic sensors Cn (n is an integer from 1 to 15) arranged in a straight line, and a detection processing circuit 32 containing a CPU (not shown), etc. . In the rod-shaped magnetic sensor array 3, 15 magnetic sensors Cn are arranged at intervals of 5 cm along its longitudinal direction. When the magnetic sensor array 3 is attached to the towing vehicle 21 along the vehicle width direction, 15 magnetic sensors Cn are arranged in a straight line along the vehicle width direction (lateral direction). According to the 15 magnetic sensors Cn arranged in the vehicle width direction, when the magnetic marker 10 is detected, the position of the magnetic marker 10 in the vehicle width direction can be detected. Based on the position of the magnetic marker 10 relative to the 15 magnetic sensors Cn, the amount of lateral deviation (lateral deviation) of the towing vehicle 21 with respect to the magnetic marker 10 can be specified.

Note that in the configuration of this example, among the 15 magnetic sensors Cn, the magnetic sensor C8 located at the center is located at the center of the towing vehicle 21. In this example, the position of the magnetic sensor C8 is set to the reference position. This reference position is treated as a position representative of the towing vehicle 21 when specifying the amount of lateral deviation of the towing vehicle 21 with respect to the magnetic marker 10.

As the magnetic sensor Cn, for example, a highly accurate MI (Magnetic Impedance) sensor may be adopted. The MI sensor is a magnetic sensor that utilizes the well-known MI effect (Magnet Impedance Effect) in which the impedance of a magnetically sensitive material such as an amorphous wire changes sensitively in response to an external magnetic field. Each magnetic sensor Cn is incorporated into the magnetic sensor array 3 so as to be able to measure the intensity of magnetism acting in the vertical direction.

The detection processing circuit 32 (FIG. 5) of the magnetic sensor array 3 is an arithmetic circuit that executes marker detection processing and the like for detecting the magnetic marker 10. Although not shown, the detection processing circuit 32 is configured using a CPU (central processing unit) that executes various calculations, memory elements such as ROM (read only memory) and RAM (random access memory), etc. has been done. The detection processing circuit 32 outputs a signal indicating that the magnetic marker 10 has been detected, the amount of lateral deviation of the towing vehicle 21 with respect to the magnetic marker 10, the traveling direction of the towing vehicle 21, etc. as a result of the detection processing.

The towing vehicle 21 is electrically configured as shown in FIG. 6, centering on a control unit 40 that controls travel. The control unit 40 includes the magnetic sensor array 3 described above, an IMU (Inertial Measurement Unit) 42 that enables inertial navigation, a motor unit 44 that rotationally drives the rear wheel 212, and outputs pulses in accordance with the rotation of the rear wheel 212. A wheel speed unit 442, a steering unit 46 that steers the front wheels 211 that are steered wheels, a map database 48, and the like are connected.

The IMU 42 is a unit that estimates the relative position and vehicle orientation of the towing vehicle 21 by inertial navigation. Although not shown, the IMU 42 includes a two-axis magnetic sensor that is an electronic compass that measures orientation, an acceleration sensor, a gyro sensor that measures angular velocity around the yaw axis, and the like. Here, the yaw axis is an axis in the vertical direction.

The map database 48 is a database that stores map data representing the shape and waiting position of the route 1R (see FIG. 1). The map data is linked to the magnetic marker 10 placed on the route 1R. For example, by referring to map data using the number of detected magnetic markers 10 after leaving the standby position, the position of the most recently detected magnetic marker 10 can be specified. Control unit 40 identifies the position of vehicle 2 on route 1R based on the position of magnetic marker 10.

The control unit 40 is a unit that includes an electronic circuit (not shown) that includes a CPU that executes various calculations, a memory element such as a ROM/RAM, and the like. The control unit 40 inputs control values to the steering unit 46 and the motor unit 44. The control value for the steering unit 46 is a commanded steering angle that is a control target for the steering angle of the front wheels 211. The control value for the motor unit 44 is a commanded rotational angular velocity that is a control target for the rotational angular velocity of the rear wheel 212. The control unit 40 controls the steering angle of the front wheels 211 via the steering unit 46 and the rotational angular velocity of the rear wheels 212 via the motor unit 44 . Through such control, the control unit 40 causes the vehicle 2 to travel so that the deviation (lateral deviation amount) of the vehicle 2 with respect to the magnetic marker 10 approaches zero.

Below, (a) magnetic measurement by a magnetic sensor array, (b) processing to determine the type of magnetic marker to be detected, (c) unipolar magnetic marker detection processing, (d) multipolar magnetic marker detection processing, (e) The contents of the azimuth measurement process using the multipolar magnetic marker will be explained in order with reference to the flowchart of FIG. These processes are all executed by the detection processing circuit 32 (magnetic sensor array 3).

(a) Magnetic measurement by the magnetic sensor array is the processing of steps S101 to S102 in FIG. (b) The process of determining the type of magnetic marker to be detected is the process of steps S103 to S104 and S114 in the figure. (c) The unipolar magnetic marker detection process is the process of steps S105 to S108 in the figure. (d) The multipolar magnetic marker detection process is the process of steps S115 to S118 in the figure. (e) The direction measurement process using the multipolar magnetic marker is the process of steps S119 to S120 in the figure.

(a) Magnetic measurement by magnetic sensor array As described above, each magnetic sensor Cn constituting the magnetic sensor array 3 has magnetic sensitivity in the vertical direction. Each magnetic sensor Cn measures the magnetic strength acting in the vertical direction, for example, at a frequency of 3 kHz. The detection processing circuit 32 of the magnetic sensor array 3 samples the vertical magnetic intensity (magnetic measurement value) measured by each magnetic sensor Cn at a frequency of 3 kHz for each magnetic sensor Cn.

In this way, the detection processing circuit 32 obtains time-series magnetic measurement values for each of the magnetic sensors C1 to C15 (FIG. 7, S101). In addition, in the configuration of this example, the positive/negative value of the magnetic measurement value by the magnetic sensor Cn is positive in the case of the N-pole magnet piece 100N, and negative in the case of the S-pole magnet piece 100S. A typical time-series distribution curve of magnetic measurement values corresponding to the unipolar magnetic marker 10A is as illustrated in FIG. 8(a). A typical time-series distribution curve of magnetic measurement values corresponding to the multipolar magnetic marker 10B is as illustrated in FIG. 9(a).

Note that FIGS. 8(a) and 9(a) show the time-series distribution of magnetic measurement values of one of the 15 magnetic sensors C1 to C15 that passes directly above or in the vicinity of the magnetic marker 10. It is a figure which illustrates a curve. The vertical axis of these figures indicates the magnitude of the magnetic measurement value, and the horizontal axis indicates the position of the vehicle 2 in the traveling direction. Note that if the vehicle 2 is moving at a constant speed, the waveform of the distribution curve will not change even if the horizontal axis is replaced with time.

Note that the point marked by the encircled number 1 in FIG. 8 is the position of the first magnet piece 100N. Points with encircled numbers 1 to 6 in FIG. 9 are the positions of each magnet piece 100 (six magnet pieces 100 in this example) constituting the multipolar magnetic marker 10B. The point marked by the encircled number 1 in FIG. 9 is the position of the first magnet piece 100S of the multipolar magnetic marker 10B. The point with the circled number 2 is the position of the second magnet piece 100N. The point with the circled number 6 is the position of the sixth and final magnet piece 100N.

The detection processing circuit 32 calculates the difference in the traveling direction of the time-series magnetic measurement values (see FIGS. 8(a) and 9(a)) by each magnetic sensor Cn. This difference in the traveling direction corresponds to a differential with respect to the position in the traveling direction. Note that the traveling direction corresponds to the time direction in the time-series magnetic measurement values. The difference in the traveling direction is effective for removing magnetism that acts nearly uniformly. Magnetism that acts uniformly and closely may include magnetism that acts from a magnetic source (for example, a mechanical device or iron footboard 19, etc.) that is larger than the magnet piece 100 forming the magnetic marker 10, or disturbance magnetism such as terrestrial magnetism. .

For example, if the difference in the traveling direction (first-order difference) is calculated for the time-series magnetic measurement values of Figs. 8(a) and 9(a), the time-series data of Fig. 8(b) or 9(b) can be obtained. It will be done. If the difference in the traveling direction (second order difference) is further calculated for these time series data, the time series data shown in FIG. 8(c) or FIG. 9(c) can be obtained. As illustrated in FIGS. 8(c) and 9(c), in the time series data of the second-order difference in the traveling direction, a negative extreme value appears corresponding to the N-pole magnet piece 100N, and a negative extremum value appears corresponding to the S-pole magnet piece A positive extreme value appears corresponding to the segment 100S.

The detection processing circuit 32 calculates 15 calculated values, which are second-order difference values in the traveling direction, for the time-series magnetic measurement values (for example, FIGS. 8(a) and 9(a)) obtained by each magnetic sensor Cn. seek. Each calculated value is a data value at one point in time among the time series data in FIGS. 8(c) and 9(c). The detection processing circuit 32 executes threshold processing regarding the absolute values of the 15 calculated values related to the magnetic sensors C1 to C15 (FIG. 7, S102). The threshold value is, for example, the value at the boundary of the hatched area in FIGS. 8(c) and 9(c).

In the threshold value processing in step S102 in FIG. 7, the presence or absence of the magnetic marker 10 to be detected is determined depending on whether any of the 15 calculated values (absolute values) obtained as described above exceeds the threshold value. If any of the 15 calculated values (absolute values) exceeds the threshold, the detection processing circuit 32 determines that a magnetic source that is a candidate for the magnetic marker 10 is present. When the detection processing circuit 32 determines that a magnetic source is present, it executes (b) a process of determining the type of magnetic marker 10 to be detected.

Note that, if only one of the 15 calculated values (absolute values) related to the magnetic sensors C1 to C15 exceeds the threshold, the detection processing circuit 32 selects the one magnetic sensor corresponding to the calculated value. Identify. If there are two or more calculated values exceeding the threshold among the 15 calculated values (absolute values), one magnetic sensor corresponding to the calculated value with the largest absolute value is identified. In this way, the detection processing circuit 32 detects one of the 15 magnetic sensors C1 to C15 that passes directly above or in the vicinity of the magnetic marker to be detected (which may be a magnetic source of disturbance). Identify the sensor.

(b) Processing for determining the type of magnetic marker to be detected When the detection processing circuit 32 of the magnetic sensor array 3 determines that a magnetic source is present as a result of the threshold processing (FIG. 7, S102: YES), A process of determining the type of magnetic marker 10 to be detected (unipolar magnetic marker 10A or multipolar magnetic marker 10B) is executed (S103). This judgment process selects whether to execute the unipolar magnetic marker detection process to detect the unipolar magnetic marker 10A or the multipolar magnetic marker detection process to detect the multipolar magnetic marker 10B. This is a process for Note that at this stage, it is unclear whether the magnetic generation source to be detected is the magnetic marker 10 or a disturbance.

The detection processing circuit 32 determines the type of the magnetic marker 10 to be detected based on the sign of the calculated value whose absolute value exceeds the threshold in the threshold processing of step S102 described above (S103). When this calculated value is negative, the detection processing circuit 32 determines that the magnetic marker 10 to be detected is the unipolar magnetic marker 10A (S103: unipolar). Then, unipolar magnetic marker detection processing is selected as the processing for detecting the magnetic marker 10 (S104). When this calculated value is positive, the detection processing circuit 32 determines that the magnetic marker 10 to be detected is a multipolar magnetic marker 10B (S103: multipolar). Then, multipolar magnetic marker detection processing is selected as the processing for detecting the magnetic marker 10 (S114).

(c) Unipolar magnetic marker detection process When the detection processing circuit 32 determines that the magnetic marker 10 to be detected is the unipolar magnetic marker 10A (FIG. 7, S103: Unipolar), the detection processing circuit 32 selects the unipolar magnetic marker detection process. (S104). The detection processing circuit 32 performs unipolar processing on time-series data (second-order difference value in the traveling direction) from one magnetic sensor identified as passing directly above or in the immediate vicinity of the magnetic marker 10 to be detected in step S102. Execute magnetic marker detection processing. If the magnetic marker 10 to be detected is not a magnetic source of disturbance but is correctly the unipolar magnetic marker 10A, the time-series data from the first magnetic sensor exhibits a distribution curve illustrated in FIG. 10. Note that the distribution curve in FIG. 10 is an excerpt from FIG. 8(c).

The detection processing circuit 32 uses the point A (FIG. 10) where the calculated value (absolute value) exceeding the threshold value was obtained in step S102 (FIG. 7) as a reference point, and selects a target section P to which the unipolar magnetic marker detection processing is applied. (Figure 10). The starting point of the target section P is a point 20 cm before point A. The end point of the target section P is a point that has passed point A by 20 cm. The detection processing circuit 32 takes in the time-series data from the above-mentioned one magnetic sensor in the target section P (FIG. 7, S105), and executes unipolar magnetic marker detection processing (S106).

The detection processing circuit 32 determines whether the distribution waveform of the time-series data in the target section P (FIG. 10) is a waveform with a peak at the negative extreme value (FIG. 7, S107). The detection processing circuit 32 makes this determination based on the degree of symmetry of the distribution waveform and the presence or absence of other extreme values. In this judgment, detection conditions are considered, such as, for example, the waveform has high symmetry around the negative extreme value, and there are no other extreme values that exceed the positive threshold or negative threshold. It is good to set it. When such detection conditions are met, the detection processing circuit 32 determines that the distribution waveform of the time series data of the target section P is a waveform caused by the unipolar magnetic marker 10A (S107: YES).

When the unipolar magnetic marker 10A is detected in this way, the detection processing circuit 32 specifies the point B (see FIG. 10) of the apex (negative side apex) of the single peak waveform. This point B is a point where the magnetic sensor array 3 is located directly above the monopolar magnetic marker 10A. Then, the detection processing circuit 32 acquires the magnetic measurement value of each magnetic sensor Cn at the point B, and detects the amount of lateral deviation, which is the lateral deviation of the vehicle 2 with respect to the magnetic marker 10 (FIG. 7, S108).

The magnetic measurement values of each magnetic sensor Cn at point B have a distribution of magnetic measurement values in the vehicle width direction, as illustrated in FIG. 11, for example. The detection processing circuit 32 identifies the position of the apex of the distribution in the figure. The apex of the distribution of magnetic measurement values in the vehicle width direction appears directly above the magnetic marker 10.

Note that it is also good to find the difference between the magnetic measurement values of two magnetic sensors adjacent in the vehicle width direction (difference in the vehicle width direction). If the difference in the vehicle width direction is calculated once for the magnetic measurement values of two magnetic sensors adjacent in the vehicle width direction (FIG. 11), a distribution waveform whose sign is inverted as shown in FIG. 12 can be obtained. According to the difference in the vehicle width direction, as in the case of the difference in the traveling direction shown in FIGS. 8 and 9, it is possible to reduce the disturbance magnetism that acts almost uniformly.

For example, in the distribution waveform of the difference value in the vehicle width direction shown in FIG. 12, a zero cross whose polarity is reversed appears directly above the magnet piece 100N forming the unipolar magnetic marker 10A. In the case of the figure, the position where the polarity is reversed is a position corresponding to C9.5, which is about halfway between C9 and C10, and C9.5 is the position of the magnet piece 100N in the vehicle width direction. As mentioned above, the distance between the magnetic sensors C9 and C10 is 5 cm. Further, as described above, the reference position of the vehicle 2 (towing vehicle 21) when specifying the amount of lateral deviation with respect to the magnetic marker 10 is the position of the magnetic sensor C8. Therefore, the lateral deviation (lateral deviation amount (absolute value)) of the vehicle 2 (towing vehicle 21) with respect to the magnetic marker 10 is (9.5-8)×5 cm=7.5 cm. The example in the figure is an example where the vehicle 2 (towing vehicle 21) has moved to the left with respect to the magnetic marker 10A. Note that the sign of the deviation in the lateral direction is positive when the vehicle 2 moves to the right with respect to the magnetic marker 10, and negative when it moves to the left. Therefore, the amount of lateral deviation in the case of FIG. 12 is -7.5 cm.

The magnetic sensor array 3 inputs the results of the unipolar magnetic marker detection process to the control unit 40. The result of the unipolar magnetic marker detection process includes information such as the fact that the unipolar magnetic marker 10A was detected, the detection time point (detection point, point B in FIG. 10), the amount of lateral deviation (lateral deviation), etc. It will be done.

(d) Multipolar magnetic marker detection processing When the detection processing circuit 32 determines that the magnetic marker 10 to be detected is the multipolar magnetic marker 10B (FIG. 7, S103: multipolar), the detection processing circuit 32 selects multipolar magnetic marker detection processing. (S114). The detection processing circuit 32 performs multi-polar magnetic processing on the time-series data (second-order difference value in the traveling direction) from the one magnetic sensor identified in step S102 as passing directly above or in the vicinity of the magnetic marker 10 to be detected. Execute marker detection processing. If the magnetic marker 10 to be detected is not a magnetic source of disturbance but is a correct multipolar magnetic marker 10B, the time-series data from the first magnetic sensor exhibits a distribution curve illustrated in FIG. 13. Note that the distribution curve in the figure is an excerpt from FIG. 9(c).

The detection processing circuit 32 uses the point A (FIG. 13) where the calculated value (absolute value) exceeding the threshold value was obtained in step S102 (FIG. 7) as a reference point, and selects a target section P to which the multipolar magnetic marker detection process is applied. (Figure 13). The starting point of the target section P is a point 20 cm before point A. The end point of the target section P is a point that has passed point A by 80 cm. The detection processing circuit 32 takes in the time series data of the target section P (target section P in FIG. 13) obtained by the above-mentioned one magnetic sensor (FIG. 7, S115), and executes the multipolar magnetic marker detection process (S116). .

The detection processing circuit 32 first identifies the positions of the positive apex and the negative apex of the distribution waveform of the time series data of the target section P (FIG. 13). The detection processing circuit 32 determines that the multipolar magnetic marker 10B has been detected when it is able to detect a magnetic change that changes periodically. The conditions for detecting the multipolar magnetic marker 10B by the detection processing circuit 32 of this example are constituted by the following requirements.

- There are three positive vertices and three negative vertices.
・Positive vertices are arranged at equal intervals.
・Negative vertices are arranged at equal intervals.
-The negative vertex is located at the midpoint between adjacent positive vertices.
- A positive vertex is located at the midpoint between adjacent negative vertices.

The detection processing circuit 32 determines that the multipolar magnetic marker 10B has been detected when all of the above requirements are met and the detection conditions are met (S117: YES). When the multipolar magnetic marker 10B can be detected in this way, the detection processing circuit 32 further detects the amount of lateral deviation (lateral deviation) with respect to the multipolar magnetic marker 10B (S118). Then, the detection processing circuit 32 inputs the result of the multipolar magnetic marker detection processing to the control unit 40. The result of the multipolar magnetic marker detection process includes information such as the fact that the multipolar magnetic marker 10B was detected, the detection time point (detection point), and the amount of lateral deviation of the multipolar magnetic marker 10B with respect to the magnet piece 100.

The detection time point of the multipolar magnetic marker 10B is preferably the time point when it passes through a predetermined representative magnet piece 100 (the time point at which it is detected). Further, it is preferable that the lateral deviation of the vehicle 2 with respect to the representative magnet piece 100 is the lateral deviation amount with respect to the multipolar magnetic marker 10B. The method for detecting the deviation in the lateral direction with respect to the magnet piece 100 is the same as in the case of the unipolar magnetic marker detection process described above.

Here, among the six magnet pieces 100 constituting the multipolar magnetic marker 10B, the N-pole magnet piece 100N located inside except for both ends serves as the origin of the magnetic force line toward the S-pole magnet pieces 100S on both sides. Become. Further, the S-pole magnet piece 100S located on the inside becomes a convergence point of the lines of magnetic force starting from the N-pole magnet pieces 100N on both sides. In this way, the inner magnet piece 100 in the multipolar magnetic marker 10B forms a large loop of magnetic lines of force by magnetically coupling with the magnet pieces 100 on both sides, and the magnetic strength acting on the outside tends to increase. . On the other hand, the magnet pieces 100 at both ends that are not adjacent to another magnet piece 100 on one side are magnetically isolated on that side. In the magnetically isolated magnet piece 100, only lines of magnetic force are formed from the north pole to the south pole of the magnet piece 100. The lines of magnetic force in this case tend to be smaller than the loop of lines of magnetic force formed by magnetically coupling with adjacent magnet pieces 100 as described above. Therefore, the representative magnet pieces 100 mentioned above include, for example, the second and third magnet pieces 100 among the six magnet pieces 100 constituting the multipolar magnetic marker 10B, and the inner side excluding the magnet pieces 100 at both ends. It is preferable to select the magnet piece 100 located at .

(e) Direction measurement process using multipolar magnetic marker When detecting the multipolar magnetic marker 10B, the detection processing circuit 32 measures the direction of the vehicle 2 using the multipolar magnetic marker 10B (S119 in FIG. 7). →S120). The detection processing circuit 32 of this example uses the second magnet piece 100 from the upstream side and the fifth magnet piece 100 among the six magnet pieces 100 constituting the multipolar magnetic marker 10B to Execute the azimuth measurement in step 2.

When the detection processing circuit 32 detects the multipolar magnetic marker 10B, the detection processing circuit 32 detects when the magnetic sensor array 3 is located directly above the second magnet piece 100 of the six magnet pieces 100 that constitute the multipolar magnetic marker 10B. (point C in FIG. 13) and the point in time when the magnetic sensor array 3 is located directly above the fifth magnet piece 100 (point D in the figure).

The detection processing circuit 32 attempts to detect the amount of lateral deviation of the vehicle with respect to the magnet piece 100 at each of the points C and D (step S119 in FIG. 7). Specifically, the detection processing circuit 32 acquires the magnetic measurement values of each magnetic sensor Cn at the point C and the point D. Then, the detection processing circuit 32 detects the amount of lateral deviation of the vehicle 2 with respect to the magnet piece 100 based on the distribution waveform in the vehicle width direction made up of the magnetic measurement values of each magnetic sensor Cn. Note that the method for detecting the amount of lateral deviation, which is the deviation in the lateral direction with respect to the magnet piece 100, is the same as the detection method described in the above unipolar magnetic marker detection process.

As illustrated in FIG. 14, when the amount of lateral deviation with respect to the second magnet piece 100 is d1 and the amount of lateral deviation with respect to the fifth magnet piece 100 is d2, the deviation θ of the orientation of the vehicle 2 with respect to the direction of the route 1R is: It can be calculated using the following formula. For example, when the vehicle 2 passes the multipolar magnetic marker 10B as shown in FIG. 14, the vehicle 2 is closer to the left side with respect to the second magnet piece 100. Therefore, the above-mentioned lateral shift amount d1 becomes a negative value. Furthermore, the vehicle 2 is closer to the right side with respect to the fifth magnet piece 100. Therefore, the above-mentioned lateral shift amount d2 becomes a positive value.

sinθ=(d2-d1)/S
θ=arcsin((d2-d1)/S)
Note that S is the distance between the second and fifth magnet pieces 100, which is 30 cm in this example.

As described above, in the vehicle system 1 of this example, the unipolar magnetic marker 10A and the multipolar magnetic marker 10B can be used depending on whether or not the installation location is affected by disturbance magnetism. For example, if there is a magnetic source that causes disturbance, such as when the path 1R crosses the iron footboard 19 or when there are magnetic tapes used by other systems or their remains in the vicinity, the magnetic marker 10 There is a risk that detection reliability may not be sufficient. This is because it becomes difficult for the vehicle 2 to distinguish between the magnetism from the magnetic source causing the disturbance and the magnetism acting from the magnetic marker 10.

In the vehicle system 1 of this example, a multipolar magnetic marker 10B in which six magnet pieces 100 are arranged in a row is arranged at a installation location where the influence of disturbance magnetism is large. When the vehicle 2 passes the multipolar magnetic marker 10B made up of six magnet pieces 100 arranged along the direction of the route 1R, regularly repeated magnetic changes occur. In particular, in the configuration of this example, the six magnet pieces 100 are configured to alternately have different magnetic polarities. Therefore, the magnetic change when the vehicle 2 passes the multipolar magnetic marker 10B is even more characteristic.

Although the iron footboard 19, magnetic tape, etc. can be sources of magnetic disturbance, the magnetic changes that occur when the vehicle 2 passes directly above or near these magnetic sources do not repeat regularly. By focusing on whether or not the magnetic change is a regularly repeated magnetic change, it is possible to distinguish the multipolar magnetic marker 10B from a magnetic source causing disturbance and to detect the multipolar magnetic marker 10B with high reliability.

Furthermore, in the vehicle system 1 of this example, based on the amount of lateral deviation of any two of the multipolar magnetic markers 10B with respect to the magnet pieces 100, the traveling direction of the vehicle 2 with respect to the direction connecting these two magnet pieces 100 is determined. Deviation is required. If the multipolar magnetic marker 10B has six magnet pieces 100 arranged on a straight line along the route 1R, it is possible to specify the deviation in the traveling direction of the vehicle 2 with respect to the direction of the route 1R. Note that the arrangement direction of the magnet pieces 100 in the multipolar magnetic marker 10B may not be along the direction of the route 1R, but may be, for example, a direction along a predetermined absolute direction.

In general, in order to specify the traveling direction of the vehicle 2, it is advantageous if the distance between the two magnet pieces 100 for which the amount of lateral deviation is determined is wide, since the traveling direction can be determined with less error. If the magnet pieces 100 at both ends of the multipolar magnetic marker 10B are combined, the distance between the two magnet pieces 100 can be maximized. However, among the six magnet pieces 100 forming the multipolar magnetic marker 10B, the magnet pieces 100 at both ends that are not sandwiched between the other magnet pieces 100 with different magnetic polarities are not sandwiched between the adjacent magnet pieces 100 as described above. Magnetic coupling may be insufficient. If the magnetic coupling is insufficient, the magnetic change in the traveling direction of the vehicle 2 tends to deviate from the ideal one, and the magnetic strength tends to decrease.

Therefore, in this example, in identifying the deviation in the traveling direction of the vehicle 2, the second magnet piece 100 and the fifth magnet piece 100 of the six magnet pieces 100 forming the multipolar magnetic marker 10B are used. do. The combination of the second and fifth magnet pieces 100 can achieve both magnetic stability and spacing, and is suitable for identifying displacement of the vehicle 2 in the traveling direction. However, in identifying the traveling direction of the vehicle 2, it is not essential to use the second and fifth combinations of the six magnet pieces 100. Among the magnet pieces 100 that constitute the multipolar magnetic marker 10B, a combination of two inner magnet pieces 100 is suitable for specifying the traveling direction of the vehicle 2.

Note that, as described above, the magnetism exerted on the vehicle 2 by the magnet pieces 100 at both ends of the multipolar magnetic marker 10B is somewhat unstable, and its magnetic strength tends to decrease. Therefore, it is also good to strengthen the magnetic force of only the magnet pieces 100 at both ends. In this case, it is possible to compensate for the tendency that the magnetic strength acting on the vehicle side from the magnet pieces located at both ends becomes low, and the magnitude of the magnetic strength that each magnet piece 100 of the multipolar magnetic marker 10B acts on the vehicle side can be compensated for. uniformity can be improved. For example, it is also possible to lay two sheet-like magnet pieces 100 on both ends of the multipolar magnetic marker 10B.

In addition, in this example, magnetic changes originating from the multipolar magnetic marker 10B are detected based on, for example, the number of positive vertices, the number of negative vertices, the interval between vertices, etc. in the distribution waveform of the time series data in FIG. The configuration is illustrated. This configuration detects a magnetic change that changes periodically, and the number of times the magnetic change is periodically repeated corresponds to the number of magnet pieces 100 that constitute the multipolar magnetic marker 10B. In addition to the methods described above, various methods for detecting such magnetic changes can be considered, such as a method that uses similarity with a periodically repeated waveform, and a method that uses the frequency of the waveform. As a method of using the degree of similarity, for example, there is a method of determining whether a correlation coefficient representing the degree of similarity with a periodically repeated waveform exceeds a threshold value. As a method using frequency, for example, there is a method of determining whether the frequency of a distribution waveform obtained by Fourier transform or the like belongs to a predetermined frequency range. Furthermore, it is also good to combine threshold processing regarding the effective value of the magnetic intensity in periodically changing magnetic changes. The effective value of the magnetic strength corresponds to, for example, the effective voltage of an alternating current whose voltage changes periodically.

In this example, a multipolar magnetic marker 10B in which six magnet pieces 100 are arranged is illustrated. In the multipolar magnetic marker 10B, the number of magnet pieces 100 arranged one-dimensionally along a straight line is preferably 4 or more and 11 or less. If the number is less than three, there is a risk that it will be difficult to distinguish from disturbance magnetism. If the number exceeds 11, the distance the vehicle 2 needs to move to detect the multipolar magnetic marker 10B becomes too long, and it takes time to detect the multipolar magnetic marker 10B.

In this example, a multipolar magnetic marker 10B made up of six magnet pieces 100 arranged one-dimensionally along the direction of the path 1R is illustrated. In the multipolar magnetic marker 10B, the predetermined direction in which the plurality of magnet pieces 100 are arranged may be any direction. For example, the multipolar magnetic marker 10B may be one in which a plurality of magnet pieces 100 are arranged along the vehicle width direction. Furthermore, the multipolar magnetic marker 10B may be one in which a plurality of magnet pieces 100 are two-dimensionally arranged.

In this example, a magnetic marker in which a plurality of individual magnet pieces 100 are arranged is exemplified as the multipolar magnetic marker 10B. Instead of this multipolar magnetic marker 10B, a tape-shaped marker tape (FIG. 15) or a sheet-shaped marker sheet (FIG. 16) may be used. A marker tape is, for example, a tape-shaped member in which a plurality of magnet pieces (magnets) are one-dimensionally connected. The marker sheet is, for example, a sheet-like member in which a plurality of magnet pieces (magnets) are two-dimensionally connected. The marker tape (or marker sheet) in which a plurality of magnet pieces are connected may be, for example, one in which a magnetic layer made of a magnetic material is laminated on a tape-shaped (or sheet-shaped) base material made of a resin material. . It is preferable to magnetize the magnetic layer of the marker tape region by region to form regions forming magnetic pieces. In the magnetized regions of this marker tape (or marker sheet), regions forming adjacent magnet pieces may be adjacent to each other, or may be arranged with a gap between them.

In the marker tape or marker sheet, it is also good to make the magnetic force of the magnetic pieces (magnets) forming the ends stronger than that of other magnetic pieces located on the inside. The end magnet pieces (magnets) in the marker tape are the magnet pieces at both ends. The end magnet piece (magnet) in the marker sheet is a magnet piece that forms the outer periphery of the sheet. In the marker sheet, it is also good to make the magnetic force of the magnet pieces located at the corners stronger than the other magnet pieces among the magnet pieces forming the outer periphery. In this case, it is possible to compensate for the tendency that the magnetic strength acting on the vehicle side from the edge of the marker tape or marker sheet becomes low, and each magnet piece (magnet) of the multipolar magnetic marker The uniformity of intensity can be improved.

In this example, the vehicle system 1 is illustrated in which the unipolar magnetic marker 10A and the multipolar magnetic marker 10B coexist, but all the magnetic markers may be the multipolar magnetic marker 10B. In this case, all magnetic markers 10 can be detected with high reliability regardless of the presence or absence of disturbance magnetism.

In this example, the vehicle system 1 for facilities such as factories is illustrated, but it may also be a vehicle system for vehicles traveling on a road that is an example of a running route. Further, in this example, the magnetic marker 10 that is affixed to the floor of a facility is illustrated, but it may be a monopolar magnetic marker 10A or a multipolar magnetic marker 10B that is made of a columnar magnet that is buried.

Although specific examples of the present invention have been described above in detail as in the embodiments, these specific examples merely disclose an example of technology included in the scope of the claims. Needless to say, the scope of the claims should not be interpreted to be limited by the configurations, numerical values, etc. of the specific examples. The scope of the claims includes techniques in which the specific examples described above are variously modified, changed, or appropriately combined using known techniques and the knowledge of those skilled in the art.

1 Vehicle system 1R route (runway)
10 Magnetic marker 10A Unipolar magnetic marker 10B Multipolar magnetic marker 100 Magnet piece (magnet)
100N N-pole magnet piece 100S S-pole magnet piece 2 Vehicle 21 Traction vehicle 23 Dolly 3 Magnetic sensor array 32 Detection processing circuit 40 Control unit 42 IMU
44 Motor unit 46 Steering unit 48 Map database Cn (C1 to 15) Magnetic sensor

Claims

A vehicle system in which magnetic markers are arranged at intervals on a vehicle running path,
The magnetic markers include at least a multipolar magnetic marker, which is a magnetic marker composed of a plurality of magnets arranged so that the magnetic polarities detected on the vehicle side are alternately different,
The vehicle has a detection processing circuit that executes processing for detecting the magnetic marker,
The detection processing circuit is capable of executing a multipolar magnetic marker detection process in which it is determined that one of the multipolar magnetic markers has been detected when a magnetic change that periodically changes repeatedly can be detected. system.
2. The vehicle system according to claim 1, wherein the multipolar magnetic marker is a single magnetic marker made up of the plurality of magnets arranged one-dimensionally or two-dimensionally.
3. The vehicle system according to claim 2, wherein among the plurality of magnets, a magnet located at an end in a one-dimensional or two-dimensional arrangement has a stronger magnetic force than other magnets.
In claim 3, each of the plurality of magnets is composed of sheet-like magnet pieces, and while the other magnet is one piece of the magnet piece, the magnet located at the end is composed of two pieces. A vehicle system comprising a stack of the above magnet pieces.
In claim 1, the multipolar magnetic marker is one magnetic marker in which the plurality of magnets are arranged along a predetermined direction,
The multipolar magnetic marker detection process includes a process of identifying the traveling direction of the vehicle with respect to the predetermined direction by using at least any two of the plurality of magnets constituting the multipolar magnetic marker. A vehicle system characterized by:
In claim 5, the multipolar magnetic marker includes at least four magnets as the plurality of magnets,
The at least two magnets used to specify the traveling direction of the vehicle are magnets other than two magnets at both ends of the plurality of magnets.
In claim 5, the multipolar magnetic marker is one magnetic marker composed of the plurality of magnets of 4 or more and 11 or less arranged at regular intervals along a straight line. A vehicle system which is one magnetic marker constituted by the plurality of magnets, 4 or more and 11 or less, arranged at regular intervals along the tangential direction of a running track, which may be a straight line or a curved line.
In claim 1, the multipolar magnetic marker is a magnetic marker made of a tape-shaped marker tape in which the plurality of magnets are arranged one-dimensionally, or a sheet-shaped marker sheet in which the plurality of magnets are arranged in a two-dimensional arrangement. A vehicle system.
9. The vehicle system according to claim 8, wherein among the plurality of magnets, a magnet located at an end of the marker tape or the marker sheet has a stronger magnetic force than other magnets.
In any one of claims 1 to 9, the magnetic marker includes a unipolar magnetic marker made of one magnet,
The detection processing circuit is configured to be capable of executing a unipolar magnetic marker detection process for detecting the unipolar magnetic marker in addition to the multipolar magnetic marker detection process.
In claim 10, the detection processing circuit is capable of executing processing for selecting either the multipolar magnetic marker detection processing or the unipolar magnetic marker detection processing, and depending on the result of the selected processing, the detection processing circuit A vehicle system configured to switch between multipolar magnetic marker detection processing and unipolar magnetic marker detection processing.
In claim 10, the multipolar magnetic marker and the unipolar magnetic marker are used depending on the magnitude of disturbance magnetism, and the multipolar magnetic marker has a disturbance magnetism that is lower than the unipolar magnetic marker. A vehicle system installed in large installation areas.
A marker detection method for detecting magnetic markers by a vehicle running on a track on which magnetic markers are arranged at intervals, the method comprising:
The magnetic markers include at least a multipolar magnetic marker, which is a magnetic marker composed of a plurality of magnets arranged so that the magnetic polarities detected on the vehicle side are alternately different,
including a detection process for detecting the magnetic marker,
The detection process includes at least a multipolar magnetic marker detection process of determining that one magnetic marker that is the multipolar magnetic marker has been detected when a magnetic change that changes periodically can be detected. Detection method.
In claim 13, the magnetic marker includes a unipolar magnetic marker made of one magnet,
including a process of determining whether the multipolar magnetic marker is to be detected or the unipolar magnetic marker is to be detected;
The detection process includes, in addition to the multipolar magnetic marker detection process, a unipolar magnetic marker detection process for detecting the unipolar magnetic marker,
A marker detection method in which either the multipolar magnetic marker detection process or the unipolar magnetic marker detection process is selectively executed depending on the result of the determining process.
Magnetic markers placed at intervals along a track so as to be detectable while the vehicle is moving,
The magnetic marker is a multipolar magnetic marker that is a single magnetic marker composed of a plurality of magnets arranged so that the magnetic polarity is alternately different,
The magnetic marker is configured to be detectable by detecting periodically and repeatedly changing magnetic changes on the vehicle side.
16. The magnetic marker according to claim 15, wherein the magnetic marker is a tape-shaped marker tape in which the plurality of magnets are one-dimensionally connected, or a sheet-like marker sheet in which the plurality of magnets are two-dimensionally connected. marker.
17. The magnetic marker according to claim 16, wherein among the plurality of magnets, a magnet located at an end of the marker tape or the marker sheet has a stronger magnetic force than other magnets.