JP5450305B2 - Magnetic marker detector - Google Patents

Description

  The present invention relates to a magnetic marker detection device. For example, the present invention relates to a magnetic marker detection device that detects a magnetic marker embedded in a road surface, and more particularly to a technique suitable for detecting a magnetic marker when an autonomously moving vehicle enters from any angle and preventing erroneous detection of the magnetic marker. .

  As background art in this technical field, technology development for autonomous movement of vehicles has been promoted for the purpose of reducing the driving load on a person driving a vehicle, preventing accidents, and automating transport operations in a factory. In particular, vehicle guidance using infrastructure such as white lines, wireless tags, magnetic markers, etc., to prevent accidents such as departure from the road leading to serious accidents and falling to low places such as downstairs and grooves. Technologies such as control and acceleration / deceleration control have been developed. Among these, magnetic markers are promising because they are robust against weather, lighting changes, dust, and the like, and can simplify the system configuration. For this reason, it is used in an autonomous movement system of various vehicles such as an ASV (Advanced Safety Vehicle), an automatic guided vehicle, and a golf cart.

  For example, in Patent Document 1, one row of magnetic markers is embedded in a straight line before the intersection of the travel route, and the magnetic marker is detected by a magnetic sensor mounted on the lower surface of the vehicle to perform stop control.

  Further, in Patent Document 2, in order to automatically determine a test area for road deviation prevention control of a vehicle, two or more rows of magnetic markers are embedded in the width direction of the traveling road before the test area, and the vehicle width direction is placed under the vehicle floor. Magnetic markers are detected by using about five magnetic sensors arranged in a straight line. By detecting that a magnetic marker exists only when a plurality of magnetic sensors simultaneously detect a magnetic intensity signal of a certain level or more, false detection is reduced.

JP 2009-301243 A JP 2001-307284 A

  It is not limited to a dedicated traveling path defined by a white line or the like like an automobile road, and when autonomously traveling in various environments, it is not known from which angle the vehicle enters with respect to the magnetic marker installed on the road surface. Therefore, it is necessary to be able to detect the magnetic marker from any angle. Further, when the magnetic marker is used as a stop line, if the braking operation is unnecessarily caused by the erroneous detection of the magnetic marker, the reliability of the operation of the autonomous traveling vehicle is lowered. Therefore, it is also necessary to reduce erroneous detection of the magnetic marker. However, since there is only one magnetic sensor in Patent Document 1, there is a problem that erroneous detection may occur when a magnetic material having the same magnetic strength as the magnetic marker exists. Moreover, in patent document 2, since the magnetic sensor is arrange | positioned at linear form, in order to detect a magnetic marker simultaneously with a several magnetic sensor with respect to various approach angles, it has several magnetic within the width | variety of a magnetic marker. It is necessary to arrange the sensors closely. However, there is a problem that if the magnetic sensors are arranged densely, there is a possibility of being susceptible to erroneous detection.

  Therefore, an object of the present invention is to provide a magnetic marker detection device including a magnetic marker and a magnetic sensor that can reduce detection of a magnetic marker and detect the magnetic marker from any angle.

  In order to solve the above problems, for example, the configuration described in the claims is adopted.

  The present application includes a plurality of means for solving the above-described problems. To give an example, a road surface based on a magnetic sensor in which at least three or more magnetic detection elements are arranged in a polygon, and a detection result of the magnetic sensor. A magnetic marker detecting means for determining whether at least two rows of magnetic markers having different magnetic poles in the direction perpendicular to the road surface have been detected, and when at least two magnetic detection elements detect magnetism having different magnetic poles in the magnetic sensor The magnetic marker detecting means determines that the magnetic marker has been detected. This can reduce false detections.

  Further, in the magnetic sensor in which the at least three or more magnetic detection elements are arranged in a polygon, it is the shortest among the perpendiculars drawn from the three vertices of a predetermined triangle existing in the polygon to the opposite sides. The length of the perpendicular is longer than the width of the gap between the two rows of magnetic markers, and the length of the longest perpendicular is shorter than the sum of the two widths of the magnetic markers of the two rows and the width of the gap. It is characterized by constituting a magnetic detection element. As a result, even when the vehicle enters the two rows of magnetic markers at various angles, the magnetic markers can be detected.

  Further, according to the width of the region of the magnetic marker that has a predetermined magnetic intensity or more, the width of the magnetic marker, the interval between the two magnetic markers, and the magnetic sensor are arranged.

  In addition, at least four or more magnetic detection elements are arranged in a regular polygon. As a result, a plurality of triangular magnetic detection elements having the same shape as the regular polygon are present. Therefore, it has a plurality of triangle-shaped magnetic marker detection functions of the same shape, and can be made redundant in parallel. Thereby, the reliability of the magnetic marker detection apparatus with respect to failure of a magnetic detection element can be improved. In the case of redundancy in parallel, it is desirable that the plurality of triangularly arranged magnetic sensors have the same shape.

  The autonomous moving vehicle includes the magnetic marker detection device, a braking device that performs braking, and a control device that controls the braking device based on an output of the magnetic marker detection device.

  Further, the autonomous mobile vehicle system includes the autonomous mobile vehicle and two rows of magnetic markers having different magnetic poles in the direction perpendicular to the road surface embedded in the road surface on which the autonomous mobile vehicle moves.

  Further, as a magnetic marker detection method, based on the detection result of the magnetic sensor in which two rows of magnetic markers having different magnetic poles in the direction perpendicular to the road surface are embedded in the road surface and at least three or more magnetic detection elements are arranged in a polygon, the road surface The magnetic marker embedded in the magnetic field is detected.

  Another feature of the present invention is a method for controlling an autonomous mobile vehicle in which a magnetic marker is detected by the magnetic marker detection method and the movement of the autonomous mobile vehicle is controlled based on the detection result.

  According to the present invention, for example, it is possible to provide a magnetic sensor and a magnetic marker that can detect a magnetic marker no matter which angle is entered, and thus it is possible to provide a magnetic marker detection device with few false detections.

It is an example of the block diagram of the magnetic marker detection apparatus in the Example of this invention. It is an example of the block diagram of the magnetic marker of 2 rows using the cylindrical permanent magnet in the Example of this invention. It is an example of arrangement | positioning explanatory drawing of the magnetic detection element in the Example of this invention. It is an example of the arrangement | positioning relationship figure of the magnetic marker of 2 rows used by arrangement | positioning description of the magnetic detection element in the Example of this invention. It is an example of arrangement | positioning explanatory drawing of the magnetic detection element and magnetic marker regarding Formula (1) in the Example of this invention. It is an example of arrangement | positioning explanatory drawing of the magnetic detection element and magnetic marker regarding Formula (2) in the Example of this invention. It is an example of the flowchart of the magnetic marker detection means in the Example of this invention. It is an example of the circuit block diagram of the magnetic marker detection means in the Example of this invention. It is an example of explanatory drawing of the output characteristic of the magnetic detection element in the Example of this invention. It is the figure which showed an example of the whole structure concept of the autonomous mobile vehicle system of embodiment in this invention.

  Hereinafter, examples will be described with reference to the drawings.

  FIG. 10 is a diagram illustrating an example of the overall configuration concept of the autonomous mobile vehicle system according to the embodiment of the present invention. The paper surface of the drawing is expressed as a road surface. Two rows of magnetic nails 2 having different magnetic poles for each row installed on the road surface are used as stop lines 3 (two rows of magnetic markers 140 having N and S poles). The stop line 3 is provided around the entry prohibition area 1 where the autonomous mobile vehicle 6 should not enter (an area where there is a risk of the vehicle falling, such as a downstairs or a bank), or on the side where the autonomous mobile vehicle 6 approaches. The autonomously moving vehicle 6 is equipped with a magnetic sensor 120 (the magnetic detection element 110 is arranged in a polygonal shape). Based on the output of the magnetic sensor 120, the braking device control means 4 detects the stop line 3. If the stop line 3 is detected based on the determination, a control signal to be braked is input from the braking device control means 4 to the braking device 5. When a control signal to be braked is input, the braking device 5 generates a braking force for braking the autonomously moving vehicle 6 and suppresses entry into the entry prohibition area 1. As shown in FIG. 10, the magnetic sensor 120, the braking device control means 4, and the braking device 5 are connected by a control line or an information line. Hereinafter, further details will be described.

  FIG. 1 is a diagram illustrating an example of a configuration of a magnetic marker detection device according to an embodiment of the present invention. The magnetic marker detection device 100 of this embodiment includes two rows of magnetic markers 140 (hereinafter referred to as magnetic line markers 140) having different magnetic poles for each row installed on the road surface. In addition, a magnetic sensor 120 including at least three magnetic detection elements 110 that detect the magnetic line marker 140 is provided. In addition, the magnetic sensor 120 includes a magnetic marker detection unit 130 that determines that the magnetic line marker 140 has been detected when at least two magnetic detection elements detect magnetism with different polarities with a certain magnetic strength or more. In the magnetic marker detection device 100, the constituent parts excluding the magnetic line marker 140 (the constituent parts on the magnetic sensor 120 side from the long chain line between the magnetic line marker 140 and the magnetic sensor 120 in FIG. 1) are determined in advance. It is mounted on an autonomous mobile vehicle that automatically travels along a route to a destination.

  Hereinafter, details of each component will be described.

  The magnetic line marker 140 used in the embodiment of the present invention is embedded in the road surface so as to surround a dangerous area such as a descending staircase, a bank, or a ditch, for example, in order to prevent a fall accident of an autonomous mobile vehicle leading to a serious accident. When an autonomous moving vehicle passes over the buried magnetic line marker 140, the magnetic sensor 120 installed on the vehicle detects the magnetic line marker 140 and activates the braking device to prevent entry into the dangerous area. it can. The magnetic line markers 140 are arranged in two rows in parallel with a predetermined interval, and the magnetic poles perpendicular to the road surface are different in each row. By detecting the magnetic line marker 140 composed of different magnetic poles, the frequency of erroneous detection is reduced as compared with the case of a single pole.

  As shown in FIG. 2, the magnetic line marker 140 may be configured such that a cylindrical permanent magnet 11 d is embedded in the road surface 11 linearly at a predetermined pitch interval p. With the drilling tool such as a drill, the insertion hole of the cylindrical permanent magnet 11d is drilled, and the surface of the cylindrical permanent magnet 11d is blocked and concealed with a resin 11c so that the cylindrical permanent magnet 11d does not come out of the ground surface. Prevent breakage such as wear, delamination and damage. By arranging the magnetic poles on the upper surface of the cylindrical permanent magnet 11d in a straight line and adjusting the pitch interval, a perpendicular magnetic field having a substantially constant strength can be continuously formed in the extending direction of the magnetic line marker 140. it can. Thereby, the magnetic line marker 11a with the magnetic pole in the direction perpendicular to the road surface 11 and the magnetic line marker 11b with the N pole can be configured. As another configuration, a magnetic tape may be used. The present invention is not limited to the type of magnetic marker, and may be any one that can form a constant vertical magnetic field strength continuously in a straight line. Further, the place where the magnetic line marker 140 is installed is not limited to the descending staircase, the bank, or the groove, but may be installed at a place where it is desired to forcibly brake.

  Next, the magnetic sensor 120 will be described. The magnetic sensor is composed of three or more magnetic detection elements 110, and is arranged on the lower surface of the autonomous mobile vehicle in order to detect the magnetic line marker 140 installed on the road surface. The magnetic detection element 110 is composed of a magnetic pole and a Hall element that can detect the magnetic intensity, and a voltage corresponding to the magnetic pole and the magnetic intensity is output as an analog value. The present invention is not limited to the type of magnetic detection element, and any element can be used as long as it can detect the magnetic pole and magnetic strength. For example, a magnetic impedance element, a coil, etc. are mentioned.

  Even if an autonomously moving vehicle enters the magnetic line marker 140 from various angles, at least three magnetic detection elements arranged in a triangular shape are required to simultaneously detect two rows of magnetic line markers. . Hereinafter, the arrangement of the three magnetic detection elements 110a, 110b, and 110c will be described. As shown in FIG. 3, the three magnetic detection elements 110a, 110b, and 110c are arranged in a triangle. Here, let Ha, Hb, and Hc be the lengths of the legs and the vertices of the perpendicular line that descends from each vertex of the triangle.

Next, as shown in FIG. 4, in the magnetic field formed in the extension direction of the magnetic marker line 11a of the S pole and the magnetic marker line 11b of the N pole, the perpendicular magnetic field of a certain value or more that can be detected by the magnetic detection element. The width of the magnetic field detectable region 12a for the south pole magnetic marker line 11a and the magnetic field detectable region 12b for the north pole magnetic marker line 11b (hereinafter referred to as a magnetic field detectable region) is W, and the magnetic field can be detected. Let D be the distance between the region 12a and the magnetic field detectable region 12b. Since the magnetic field detectable region is a region including the size of the magnetic detection element, in FIGS. 3, 4 and 5, each of the magnetic detection elements 110a, 110b, and 110c is represented by a circle. Note that the size of the magnetic detection element is regarded as a point. Here, in order to detect the two magnetic marker lines 11a and 11b simultaneously from various angles by the three magnetic detection elements 110a, 110b, and 110c, the lengths Ha, The length Lmin of the shortest line segment in Hb and Hc and the length Lmax of the longest line segment should satisfy the conditions shown in the following expressions (1) and (2). In the triangle shown in FIG. 3, Lmin is Ha and Lmax is Hc.
Lmin> D (Formula 1)
Lmax <D + 2W (Formula 2)

  Expression (1) is a conditional expression when the arrangement interval of magnetic detection elements capable of detecting two rows of magnetic line markers is the shortest. As shown in FIG. 5, all of the magnetic detection elements 110a, 110b, and 110c can detect two magnetic fields in an arrangement in which the perpendicular line of length Ha is perpendicular to the two rows of magnetic field detectable regions 12a and 12b. This means a condition for preventing protrusion of the gap between the regions (region of width D in FIG. 5).

  Similarly, Expression (2) is a conditional expression when the arrangement interval of the magnetic detection elements capable of detecting two rows of magnetic line markers is the longest. As shown in FIG. 6, in the arrangement in which the sides of the length Hc are perpendicular to the two rows of magnetic field detectable regions 12a and 12b, the magnetic detection elements 110a, 110b, and 110c are outside the magnetic detection region. It means a condition to prevent it from protruding.

  By configuring the arrangement of the magnetic detection elements 110a, 110b, 110c and the widths and intervals of the magnetic field detectable regions 12a, 12b so as to satisfy the expressions (1) and (2), it is possible to enter from which direction. However, a magnetic sensor capable of detecting the magnetic field detectable regions 12a and 12b can be configured. In actual design, it is desirable to design in the shape of an equilateral triangle. Thereby, an increase in design parameters can be suppressed.

  The case where three magnetic detection elements 110a, 110b, and 110c are used has been described above. However, when four or more magnetic detection elements are used, the magnetic detection elements are arranged in a polygon and are inherent in the polygon. What is necessary is just to comprise the arrangement | positioning which satisfy | fills Formula (1) (2) with respect to a predetermined triangle. By arranging the magnetic detection elements so as to satisfy the expressions (1) and (2) with respect to Lmin and Lmax related to a predetermined triangle, a magnetic sensor that can be detected from any angle can be configured. . When the polygon is a regular polygon, the regular polygon includes a plurality of triangles having the same shape. By performing the design for the plurality of triangles, the detection function of the magnetic line marker 140 can be made redundant in parallel. Therefore, by increasing the number of magnetic detection elements, the reliability of the magnetic marker detection device according to the embodiment of the present invention against a failure of the magnetic detection elements can be improved. For example, (1) when the regular polygon is a quadrangular shape, paying attention to an isosceles triangle having two sides on the outer periphery, there are four triangles having the same shape as the number of vertices. Considering each of the four apexes as a magnetic detection element, even if one magnetic detection element fails, three magnetic detection elements constituting one triangle remain, and magnetic detection by a triangular magnetic detection element is possible. Become. Next, for example, (2) when the regular polygon is a pentagon, paying attention to an isosceles triangle having two sides on the outer periphery, there are five triangles having the same shape as the number of vertices. Considering each of the five apexes as a magnetic detection element, even if one magnetic detection element fails, four magnetic detection elements that make up two isosceles triangles remain, and magnetic detection by the triangular magnetic detection element is possible. It becomes. In this case, since at least one pair of triangular magnetic detection elements remains until the failure of two adjacent sensors, magnetic detection by the triangular magnetic detection element becomes possible. Further, (3) the same regular polygon is a pentagon, but when attention is paid to an isosceles triangle having one side of the outer periphery as an edge, there are five triangles having the same shape as the number of vertices. . In this case, if each of the five vertices is considered as a magnetic detection element, even if one magnetic detection element fails, there are three magnetic detection elements constituting one isosceles triangle and one other magnetic detection element. A total of four magnetic detection elements remain, and magnetic detection by a triangular magnetic detection element becomes possible.

  Next, processing in the magnetic marker detection unit 130 will be described according to the flowchart of FIG. When the process is “started”, first, in step 500, a voltage signal corresponding to the magnetic pole and magnetic intensity of each magnetic detection element output from the magnetic sensor 120 is received. Next, in step 510, it is determined whether or not there are signals of both the N and S magnetic poles having a magnetic intensity equal to or greater than a certain value in the received signal. Note that the value of the magnetic intensity above a certain value is the same as the value used for setting the magnetic field detectable region. If it is determined that the signals of both the N and S magnetic poles exist at the same time, it is determined (determined) in step 520 that the magnetic line marker 140 has been detected. If it does not exist, it is determined (determined) in step 530 that the magnetic line marker 140 has not been detected. By using the above processing, the magnetic marker detection means 130 can be configured by a simple digital circuit.

  FIG. 8 is a digital circuit diagram of the magnetic marker detection means 130 for the three magnetic detection elements 110a, 110b, and 110c. It is configured to output a Hi signal when any two of the three magnetic detection elements 110a, 110b, and 110c detect the N pole or the S pole, and output a Low signal otherwise. .

  As shown in FIG. 9, each magnetic detection element 110a, 110b, 110c outputs an analog voltage according to the magnetic flux density. The voltages V1 and V2 are applied to the comparator 300a shown in FIG. 8 so that the S pole is determined when the output is V1 [V] or less and the N pole is determined when the output is V2 [V] or more.

  For example, the circuit of FIG. 8 is connected to a braking device mounted on an autonomous mobile vehicle, and the braking device is operated according to Hi-Low, thereby detecting the magnetic line marker 140 installed in front of the dangerous area and detecting the vehicle. Can be stopped. Note that the circuit of FIG. 8 is an example, and the type and number of logic circuits are not limited. Further, a relay switch or an analog circuit may be used. Further, the magnetic marker detection means 130 may be executed by an arithmetic device such as a microcomputer or a multiprocessing unit.

  The embodiment of the present invention has been described above. The present invention is not limited to being realized as the embodiment. For example, the magnetic line marker 140 may be used as a tracking line for autonomously moving vehicles.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Further, each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files that realize each function can be stored in a memory, a recording device such as a hard disk or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD. Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

11 Road surface 11a S-pole magnetic marker line 11b N-pole magnetic marker line 11c Resin 11d Cylindrical permanent magnet
12a Magnetic field detectable region 12b for magnetic marker line 11a of S pole Magnetic field detectable region 100 for magnetic marker line 11b of N pole Magnetic marker detection device 110 Magnetic detection elements 110a, 110b, 110c Magnetic detection element 120 Magnetic sensor 130 Magnetic marker detection Means 140 Two-line magnetic line marker 300 Digital circuit 300a of magnetic marker detection means Comparator

Claims (7)

A magnetic sensor in which at least three or more magnetic detection elements are arranged at positions that form polygonal vertices ;
Magnetic marker detection means for determining whether at least two rows of magnetic markers having different magnetic poles in the road surface vertical direction embedded in the road surface are detected based on the detection result of the magnetic sensor;
The magnetic detection element has a width of a gap between the magnetic markers having the shortest perpendicular line length among the perpendicular lines drawn from three vertices of a predetermined triangle in the polygon to the opposite sides. It is arranged so that the length of the longest and longest perpendicular line is shorter than the sum of the two widths of the two rows of magnetic markers and the width of the gap. In the magnetic sensor, at least two magnetic detection elements are magnetic poles. A magnetic marker detection device, wherein when a different magnetism is detected, the magnetic marker detection means determines that the magnetic marker has been detected. In claim 1,
The magnetic sensor arranged in the polygon has four or more magnetic detection elements,
In each of a plurality of predetermined triangles inherent in the polygon, among the perpendiculars drawn from the three vertices of the predetermined triangle to the opposite sides, the shortest perpendicular length is the two rows of magnetism. The magnetic detection element is arranged so that the length of the longest perpendicular line is longer than the width of the marker gap and shorter than the sum of the two widths of the two rows of magnetic markers and the width of the gap. Magnetic marker detection device. In claim 1 or 2,
In the magnetic sensor, at least three or more magnetic detection elements are arranged in a regular polygon. A magnetic marker detection device according to any one of claims 1 to 3 ,
A braking device for braking,
An autonomous mobile vehicle comprising: a control device that controls the braking device based on an output of the magnetic marker detection device. An autonomous mobile vehicle according to claim 4 ,
An autonomous mobile vehicle system comprising: two rows of magnetic markers having different magnetic poles in the direction perpendicular to the road surface embedded in a road surface on which the autonomous mobile vehicle moves. Disposing at least two rows of magnetic markers having different magnetic poles in the direction perpendicular to the road surface;
Disposing at least three or more magnetic detection elements of the magnetic sensor at positions that form vertexes of a polygon;
The magnetic detection element has a width of a gap between the magnetic markers having the shortest perpendicular line length among the perpendicular lines drawn from three vertices of a predetermined triangle in the polygon to the opposite sides. A longer and longest vertical line is arranged so that it is shorter than the sum of the two widths of the two rows of magnetic markers and the width of the gap;
A method of detecting a magnetic marker, comprising: determining that the magnetic marker has been detected when at least two magnetic detection elements of the magnetic sensor detect magnetism having different magnetic poles. A control method for an autonomous mobile vehicle, wherein the magnetic marker is detected by the magnetic marker detection method according to claim 6 and the movement of the autonomous mobile vehicle is controlled based on the detection result.

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