阅读说明：本技术 位置检测系统以及行驶系统 (Position detection system and travel system ) 是由 角口谦治 山田康武 于 2019-03-19 设计创作，主要内容包括：位置检测系统(150)具备：两列磁铁列(510、520),是由在检测方向上将排列图案作为一个周期并周期性地反复排列的多个磁铁(511～514、521～524)构成的两列磁铁列,且在检测方向上的特定的位置,磁铁列(510)的磁铁与磁铁列(520)的磁铁以具有不同的极性的面相互对置；磁传感器(600),配置在两列磁铁列之间,且该磁传感器在X轴方向上相对于两列磁铁列的相对的位置能够变化；以及决定部(141),基于磁传感器的检测值决定磁传感器相对于两列磁铁列的规定方向上的位置。(A position detection system (150) is provided with: two rows of magnet rows (510, 520) each of which is composed of a plurality of magnets (511-514, 521-524) arranged periodically and repeatedly with an arrangement pattern as one cycle in the detection direction, and in which the magnets of the magnet rows (510) and the magnets of the magnet rows (520) are opposed to each other with surfaces having different polarities at a specific position in the detection direction; a magnetic sensor (600) which is disposed between the two rows of the magnets and whose relative position in the X-axis direction with respect to the two rows of the magnets can be changed; and a determination unit (141) that determines the position of the magnetic sensor in the predetermined direction with respect to the two rows of magnet rows, based on the detection value of the magnetic sensor.)

1. A position detection system for detecting the position of a magnetic sensor with respect to a magnet row, the position detection system comprising:

two rows of magnet rows each including a plurality of magnets arranged in a periodic manner in a detection direction with an arrangement pattern as one cycle, the magnets of one magnet row and the magnets of the other magnet row being opposed to each other at a specific position in the detection direction on a plane having a different polarity;

a magnetic sensor disposed between the two rows of the magnet rows, the magnetic sensor being changeable in relative position to the two rows of the magnet rows in the detection direction; and

a determination unit that determines a position of the magnetic sensor in the detection direction with respect to the two rows of the magnet rows based on a detection value of the magnetic sensor,

the magnetic sensor includes a first detection element for detecting a magnetic flux density, and a second detection element for detecting a magnetic flux density, the second detection element being disposed at a position distant from the first detection element in the detection direction by a distance of (2A +1)/4 cycles of the array pattern, A being an integer of 0 or more,

the determination unit calculates a first electrical phase angle by calculating an arctangent of a first ratio, which is a ratio of a first magnetic flux density detected by the first detection element and a second magnetic flux density detected by the second detection element, and determines the position of the magnetic sensor using the calculated first electrical phase angle.

2. The position detection system according to claim 1,

the determination unit determines, as the position of the magnetic sensor, a position that is associated with the first electrical phase angle in the first relationship information, using the calculated first electrical phase angle and first relationship information indicating a relationship between the first electrical phase angle and the position.

3. The position detection system according to claim 1,

the magnetic sensor includes:

a third detecting element that detects a magnetic flux density, the third detecting element being disposed at a position distant from the first detecting element in the detection direction by a distance of (4B +1)/8 cycles of the array pattern, B being an integer of 0 or more; and

a fourth detecting element that detects a magnetic flux density, the fourth detecting element being disposed at a position distant from the third detecting element in the detection direction by a distance of (2C +1)/4 cycles of the array pattern, C being an integer of 0 or more,

the determination unit further performs the following processing:

(1) calculating a second electrical phase angle by calculating an arctangent of a second ratio, which is a ratio of a third magnetic flux density detected by the third detecting element and a fourth magnetic flux density detected by the fourth detecting element;

(2) calculating an average electrical phase angle which is an arithmetic mean of the first electrical phase angle and the second electrical phase angle; and

(3) and determining a position in the second relationship information, which corresponds to the average electrical phase angle, as the position of the magnetic sensor, using the calculated average electrical phase angle and second relationship information indicating a relationship between the average electrical phase angle and the position.

4. The position detection system according to any one of claims 1 to 3,

the arrangement pattern of the two rows of magnet rows is a halbach arrangement.

5. The position detection system according to any one of claims 1 to 4,

the first detection element and the second detection element are hall elements, respectively, and are arranged in a direction in which the detection surface faces the one magnet row.

6. The position detection system according to any one of claims 1 to 4,

the first detection element and the second detection element are each a coil and are arranged in a direction in which an axis of the coil is perpendicular to the two rows of the magnet rows.

7. A travel system is provided with:

the position detection system of any one of claims 1 to 6;

a traveling vehicle driven by a linear motor having the two rows of magnet rows as a fixed member or a movable member; and

and a controller that controls traveling of the traveling vehicle by driving the linear motor in accordance with the position of the magnetic sensor detected by the position detection system.

Technical Field

The present invention relates to a position detection system for detecting a position by detecting magnetic flux densities of a plurality of magnet arrays, and a travel system using the position detection system.

Background

Patent document 1 discloses a displacement sensor that detects a position with a magnetic scale as a reference by a magnetic element.

Patent document 1: international publication No. 2014/109190

However, in the technique of patent document 1, it is not considered to use two rows of magnet rows arranged with opposite poles facing each other at a specific position as the magnetic scale. In this case, there is a problem that it is difficult to appropriately detect the position of the displacement sensor with respect to the two rows of magnet rows. The item (which is a basic knowledge of the invention) describes in detail the difficulty of detecting the position of the displacement sensor when the two rows of magnet rows are used.

Disclosure of Invention

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a position detection system in which a magnetic sensor arranged at a position between two rows of magnet rows arranged with opposite poles facing each other at a specific position can appropriately detect the position of the magnetic sensor with respect to the two rows of magnet rows.

In order to achieve the above object, a position detection system according to an aspect of the present invention is a position detection system that detects a position of a magnetic sensor with respect to a magnet row, including: two rows of magnet rows each including a plurality of magnets arranged in a periodic manner in a detection direction with an arrangement pattern as one cycle, the magnets of one magnet row and the magnets of the other magnet row being opposed to each other at a specific position in the detection direction on a plane having a different polarity; a magnetic sensor disposed between the two rows of the magnet rows, and capable of changing a relative position of the magnetic sensor with respect to the two rows of the magnet rows in the detection direction; and a determination unit configured to determine a position of the magnetic sensor in the detection direction with respect to the two rows of magnets based on a detection value of the magnetic sensor, wherein the magnetic sensor includes a first detection element configured to detect a magnetic flux density, and a second detection element configured to detect the magnetic flux density, the second detection element being disposed at a position distant from the first detection element in the detection direction by a distance of (2A +1)/4 cycles (a is an integer of 0 or more) of the array pattern, and the determination unit calculates a first electrical tangent by calculating a first ratio that is a ratio of a first magnetic flux density detected by the first detection element and a second magnetic flux density detected by the second detection element, and determines the position of the magnetic sensor using the calculated first electrical phase angle.

Accordingly, the position detection system determines the position using the first detection element and the second detection element disposed at a position distant from the first detection element in the detection direction by a distance of (2A +1)/4 cycles of the array pattern. Therefore, even in a position detection system having two magnet rows arranged with opposite poles facing each other at a specific position, the relative position of the magnetic sensor with respect to the two magnet rows can be appropriately detected.

Further, the determination unit may determine, as the position of the magnetic sensor, a position associated with the first electrical phase angle in the first relationship information, using the calculated first electrical phase angle and first relationship information indicating a relationship between the first electrical phase angle and the position.

Therefore, the position detection system can easily determine the relative position of the magnetic sensor with respect to the two rows of the magnet rows using the detection results of the first detection element and the second detection element.

In addition, the magnetic sensor may include: a third detection element that detects a magnetic flux density, the third detection element being disposed at a position distant from the first detection element in the detection direction by a distance of (4B +1)/8 cycles (B is an integer of 0 or more) of the array pattern; and a fourth detection element that detects a magnetic flux density, the fourth detection element being disposed at a position distant from the third detection element in the detection direction by a distance of (2C +1)/4 cycles (C is an integer of 0 or more) of the array pattern, wherein the determination unit further performs a process of (1) calculating a second electrical phase angle by calculating an arctangent of a second ratio, which is a ratio of a third magnetic flux density detected by the third detection element and a fourth magnetic flux density detected by the fourth detection element, (2) calculating an average electrical phase angle, which is an arithmetic average of the first electrical phase angle and the second electrical phase angle, and (3) determining a position corresponding to the average electrical phase angle in the second relationship information as the position of the magnetic sensor, using the calculated average electrical phase angle and second relationship information indicating a relationship between the average electrical phase angle and the position.

Accordingly, the position detection system can eliminate harmonic components of the triple wave and the quintuple wave by obtaining the arithmetic mean of the first electrical phase angle and the second electrical phase angle. Therefore, the position detection system can reduce the cycle error of the magnetic fields of the two rows of magnet rows, and can accurately determine the position of the magnetic sensor.

Further, the arrangement pattern of the two magnet rows may be a halbach arrangement.

Therefore, the magnetic flux can be concentrated between the two rows of magnet rows. For example, when a linear motor having two rows of magnet rows as a stationary member or a movable member is provided, the linear motor can efficiently obtain a driving force by electromagnetic induction.

Further, the first detection element and the second detection element may be hall elements, respectively, and may be arranged in a direction in which the detection surface faces the one magnet row.

Therefore, the first and second detection elements can effectively detect the magnetic flux density in the direction perpendicular to the magnet row.

The first detection element and the second detection element may be coils, respectively, and may be arranged in a direction in which an axis of the coils is perpendicular to the two rows of the magnet rows.

Therefore, the first and second detection elements can effectively detect the magnetic flux density in the direction perpendicular to the magnet row.

Further, a traveling system according to an aspect of the present invention includes: the above position detection system; a traveling vehicle driven by a linear motor having the two rows of magnet rows as a fixed member or a movable member; and a controller that controls traveling of the traveling vehicle by driving the linear motor in accordance with the position of the magnetic sensor detected by the position detection system.

In this way, the two rows of magnet rows used as the stator or the mover of the linear motor for running the first conveyance carriage can be used in the position detection system for detecting the position of the running vehicle. Therefore, the manufacturing cost can be reduced.

The article transport device of the present invention can appropriately detect the position of the magnetic sensor with respect to the two rows of magnet rows when the magnetic sensor is disposed at a position between the two rows of magnet rows arranged with the opposite poles facing each other at a specific position.

Drawings

Fig. 1 is a perspective view for explaining the configuration of an article transport apparatus according to the embodiment.

Fig. 2 is a schematic view of the article transport apparatus in the embodiment as viewed from the traveling direction of the transport carriage.

Fig. 3 is a block diagram showing a functional configuration of the article transport apparatus according to the embodiment.

Fig. 4 is a schematic diagram showing an example of the configuration of the position detection system.

Fig. 5 is a magnetic flux density waveform showing a magnetic flux density distribution in the X-axis direction in a space between two rows of magnets.

Fig. 6 is a block diagram showing an example of a functional configuration of the position sensor.

Fig. 7 is a flowchart showing an example of the operation of the position detection system.

Fig. 8 is a diagram showing the result of performing fast fourier transform on the magnetic flux density waveform of fig. 5.

Fig. 9 is a diagram showing a position detection error of a position calculated using the first and second electrical phase angles, respectively, and a position detection error of a position calculated using the average electrical phase angle.

Fig. 10 is a schematic diagram showing an example of the configuration of a position detection system according to a modification.

Detailed Description

(knowledge forming the basis of the present invention)

Patent document 1 discloses a technique for detecting the position of a magnetic sensor with respect to a magnet array in which S poles and N poles are alternately arranged. Such a magnet array forms a magnetic field in which magnetic lines of force are oriented in different directions depending on the position in the arrangement direction of the magnet array.

A technique is known in which the position of the magnetic sensor with respect to the arrangement direction of the magnet rows is determined by using magnetic lines of force having such a shape. In this case, for example, the magnetic sensor includes two detection elements for detecting the magnetic flux density at a specific position (same phase) on the magnetic sensor. One of the two detection elements faces the magnet array and detects a vertical component, which is a component of magnetic flux density in a direction perpendicular to the magnet array. The other of the two detection elements is parallel to the magnet row and detects a component of the magnetic flux density parallel to the magnet row, that is, a parallel component. The magnetic sensor calculates an electrical phase angle arctan R by calculating the arctangent of the ratio R of the magnetic flux densities detected by the two detection elements, and further can calculate the position of the magnetic sensor based on the electrical phase angle arctan R.

In the above-described technique, since there are a perpendicular component and a parallel component of the magnetic flux density, the position of the magnetic sensor can be detected by detecting the magnetic flux density at one position as described above.

On the other hand, in two rows of magnet rows extending in a predetermined direction, a configuration is assumed in which the N-pole and the S-pole face each other in the facing direction of the two rows of magnet rows. In this configuration, the magnetic flux lines generated from the N-pole of one magnet row are directed directly toward the S-pole of the other magnet row. Therefore, a magnetic field in which the perpendicular component of the magnetic flux density is extremely large as compared with the parallel component can be formed. This magnetic field can be used, for example, in a linear motor in which a movable element is disposed between two rows of magnets in a direction in which the movable element receives a magnetic force of a perpendicular component of a magnetic flux density, thereby efficiently supplying the magnetic force to the movable element.

However, if the magnet array is a magnet array effective for a linear motor, the perpendicular component of the magnetic flux density is extremely large compared to the parallel component, and therefore, in the magnetic sensor including the detection element for detecting the parallel component and the perpendicular component of the magnetic flux density at a specific position as described above, it is difficult to detect a change corresponding to the position of the magnetic flux density. Therefore, there is a problem that even if the magnetic sensor having this configuration uses the detection result of the detection element, the electric phase angle cannot be calculated, and the position of the magnetic sensor cannot be calculated. The inventors of the present disclosure have found a magnetic sensor configured to efficiently detect the position of a magnet row forming a magnetic field in which the perpendicular component of the magnetic flux density is extremely large compared to the parallel component, and a calculation method for calculating the position using the detection result of the magnetic sensor.

Hereinafter, an article transport apparatus including a position detection system and a travel system according to an embodiment of the present invention will be described with reference to the drawings. The drawings are schematic and are not necessarily strictly illustrated.

The embodiments described below show a specific example of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connection modes of the constituent elements, steps, order of the steps, and the like shown in the following embodiments are merely examples, and do not limit the present invention. In the following embodiments, components not described in the independent claims representing the highest concept are described as arbitrary components.

(embodiment mode)

[ constitution ]

First, an outline of the article transport apparatus 100 according to the embodiment of the present invention will be described with reference to fig. 1 and 2.

Fig. 1 is a perspective view for explaining the configuration of an article transport apparatus according to the embodiment. Fig. 2 is a schematic view of the article transport apparatus in the embodiment as viewed from the traveling direction of the transport carriage. In the article transport apparatus 100 shown in fig. 1, the travel path has an annular shape in a plan view, but in the following description, a straight line section in which the travel direction is the X-axis direction will be described. In other words, the following description will be made with the traveling direction being the X-axis direction.

As shown in fig. 1 and 2, the article transport apparatus 100 is a travel system including a travel rail 110, a primary-side fixed element group 120, a first transport carriage 210, and a second transport carriage 220. Further, the article transport apparatus 100 includes a power source 130 and a position sensor 140.

The travel rail 110 is a member disposed along a travel path (a path extending in the X-axis direction in fig. 1 and 2). Specifically, the running rail 110 is two elongated members arranged in a direction orthogonal to the running path and extending along the running path, and is made of metal such as aluminum or aluminum alloy, for example. The travel rail 110 may be made of resin. In the present embodiment, as shown in fig. 1, the travel rail 110 includes a transfer section a11 that intersects the conveyance path 410 of the conveyance device 400 that conveys the article 10 and transfers the article 10 to and from the conveyance device 400.

The primary-side fastener group 120 is an example of a fastener group including a plurality of fasteners. The primary side fixed member group 120 is arranged along the travel path. Specifically, the primary side fixed element group 120 is configured by a long plate-shaped substrate extending along the travel path and a plurality of coils arranged in a longitudinal direction of the substrate. In other words, the plurality of coils actually function as the plurality of fasteners constituting the primary-side fastener group 120, respectively. Further, the substrates of the primary side fixture group 120 are arranged parallel to the horizontal direction (in other words, parallel to the XY plane).

Since the plurality of coils constituting the primary-side fixed element group 120 are individually controlled by the controller 300 (see fig. 3), the coils generate magnetic fields independently. In this way, the primary fixed group 120 is controlled by the controller 300 alone, and thereby magnetically acts on the secondary movable element 211 provided on the first conveying carriage 210 and the second conveying carriage 220. Accordingly, the primary side fixed group 120 gives a force to the secondary side movable element 211 in the X axis direction, and moves the first conveyance carriage 210 and the second conveyance carriage 220 on the travel rail 110.

The power source 130 is disposed on the travel path, and applies a force to the transfer unit 212 included in the first conveyance carriage 210 and the second conveyance carriage 220 to operate the transfer unit 212.

The position sensor 140 is a sensor for detecting the position of each of the first conveyance carriage 210 and the second conveyance carriage 220. The position sensor 140 is a magnetic sensor that detects the position of a permanent magnet as a detection target portion (see below) provided on each of the first and second conveyance carriages 210 and 220.

The position sensor 140 is disposed along the travel path. Specifically, the position sensors 140 are disposed in a section in which the primary-side fixed element group 120 is disposed. Specifically, a plurality of position sensors 140 are disposed adjacent to a plurality of primary side fixed element groups 120 disposed in predetermined length units on the travel path. Thus, the article transport apparatus 100 can control the traveling operation of each of the first transport carriage 210 and the second transport carriage 220 by controlling the primary side fixture group 120 corresponding to the position of each of the first transport carriage 210 and the second transport carriage 220 detected by the position sensor 140.

The first conveyance cart 210 will be specifically described with reference to fig. 2.

The first conveyance carriage 210 is a conveyance carriage that has a secondary movable element 211, and the secondary movable element 211 travels on the travel guide rail 110 by receiving magnetic action from the primary fixed element group 120 to convey an article. The first conveyance carriage 210 includes a transfer unit 212, a frame 217 serving as a base, and a roller 218 for traveling provided on the frame 217, in addition to the secondary movable element 211.

The secondary-side movable element 211 is an example of a movable element and also serves as a detected portion. The secondary mover 211 is composed of, for example, a plurality of permanent magnets. The plurality of permanent magnets constituting the secondary movable element 211 are arranged in line in the traveling direction of the first conveyance carriage 210. The secondary movable element 211 is disposed below the frame 217 so as to face both sides of the primary fixed element group 120 in the Z-axis direction in a state where the first conveyance carriage 210 is disposed on the travel rail 110. In other words, the secondary mover 211 is configured such that a plurality of permanent magnets are arranged in two rows on both sides of the primary stator group 120 in the Z-axis direction. The plurality of permanent magnets in each two rows are arranged in the X-axis direction. The first conveyance carriage 210 travels by a ground-based primary linear motor system including the primary-side stator group 120 arranged on a predetermined path and the secondary-side movable element 211 included in the first conveyance carriage 210 so as to be able to individually stop or accelerate/decelerate.

The transfer unit 212 receives the force from the power source 130 and transfers the article in a direction (Y-axis direction) intersecting the travel path. In the present embodiment, the transfer unit 212 transfers articles in the Y-axis direction, but the transfer unit is not limited to the Y-axis direction, and may not be strictly orthogonal to a predetermined path as long as the transfer unit is oriented in a direction intersecting the travel path (the travel direction of the first conveyance carriage 210). For example, the transfer unit 212 may intersect the travel path (the travel direction of the first conveyance carriage 210) at 45 degrees.

Specifically, the transfer unit 212 includes a secondary-side rotating member 213, a transfer conveyor 214, and a conveyor belt 215. The secondary-side rotating member 213 rotates by a rotating shaft extending along the traveling direction of the first conveying carriage 210. The secondary rotating member 213 is rotated by a magnetic force based on a magnetic action of the primary fixing member 131 from the power source 130, and drives the transfer conveyor 214. The secondary-side rotator 213 is provided at the front end of a support member 219 extending from the frame 217 to the Z-axis negative direction side and extending from the end of the Z-axis negative direction side to the Y-axis negative direction side. The support member 219 has an L-shape when viewed from the X-axis direction.

The first conveyance carriage 210 may not have the transfer unit 212, and the article conveyance device 100 may not have the power source 130.

Here, the power source 130 will be described in detail with reference to fig. 2.

The power source 130 is constituted by a primary side fixing member 131 having a substantially C-shaped cross section and disposed in a substantially cylindrical region through which the secondary side rotating member 213 included in the first conveyance carriage 210 passes when the first conveyance carriage 210 travels, at a position surrounding the region. The power source 130 generates a predetermined magnetic field in the primary side stator 131, thereby applying a magnetic force based on a magnetic action to the secondary side rotor 213 included in the first carriage 210. The primary-side fixture 131 has a shape surrounding a range of approximately 270 degrees around the traveling direction (X-axis direction) of the first carriage 210. In other words, the primary-side fixing element 131 has a shape in which a part of the side surface of the cylindrical side surface corresponding to approximately 90 degrees is removed. The primary-side stator 131 is disposed in the cylindrical shape with the portion of the cylindrical shape removed facing the positive Y-axis direction. The power source 130 is disposed in a section in the travel path in which the transfer unit 212 of the first conveyance cart 210 is to be driven, and drives the transfer unit 212 of the first conveyance cart 210 by transferring the article 10 from the outside or by being controlled by the controller 300 when the article 10 is transferred to the outside while the first conveyance cart 210 passes through the section.

The transfer conveyor 214 is driven in the cross direction by the secondary-side rotating member 213 via the conveyor belt 215. The transfer conveyor 214 is, for example, a conveyor belt driven in the Y-axis direction, and is disposed on the upper surface of the first conveyance carriage 210. In other words, the transfer conveyor 214 constitutes a placement surface of the article 10 on the first conveyance carriage 210, and is driven in the Y-axis direction, thereby transferring the article 10 on the outer side in the Y-axis direction from the first conveyance carriage 210 onto the upper surface of the first conveyance carriage 210 (that is, the upper surface of the transfer conveyor 214), or transferring the article 10 placed on the upper surface of the first conveyance carriage 210 from the upper surface onto the outer side in the Y-axis direction of the first conveyance carriage 210. The transfer conveyor 214 is not limited to a conveyor belt, and may be a roller conveyor.

The conveyor belt 215 is a power transmission conveyor belt that connects the rotary shaft of the secondary-side rotary member 213 to the rotary shaft for driving the transfer conveyor 214, and transmits the rotation of the rotary shaft from the secondary-side rotary member 213 to the rotary shaft for driving the transfer conveyor 214. When viewed from the X-axis direction, the conveyor belt 215 is disposed in an annular shape at a position along the frame 217 and the support member 219 of the first conveyance carriage 210. The conveyor belt 215 is formed into an annular shape by a plurality of pulleys provided on the end surfaces of the frame 217 and the support member 219 in the X-axis direction, and the conveyor belt 215 is stretched over the plurality of pulleys.

In this way, since the conveyor belt 215 is disposed in an annular shape at a position along the frame 217 and the support member 219 of the first conveyance carriage 210, a dead space caused by the disposition of the conveyor belt 215 can be reduced. In addition, since the conveyor belt 215 penetrates the frame 217 substantially vertically, the size of the opening for penetrating the frame 217 can be reduced. Therefore, intrusion of foreign matter into the inside of the chassis 217 can be suppressed.

The conveyor belt 215 is, for example, a rubber conveyor belt. The conveyor belt 215 is not limited to a rubber conveyor belt, and may be a chain.

The second conveyance carriage 220 includes a secondary-side movable element 221, a transfer unit 222, a frame 227 serving as a base, a roller 228 for traveling provided in the frame 227, and a support member 229.

The secondary-side mover 221 has the same structure as the secondary-side mover 211.

The transfer unit 222 has the same configuration as the transfer unit 212. In other words, the secondary-side rotator 223, the transfer conveyor 224, and the conveyor belt 225 of the transfer unit 222 have the same configurations as the secondary-side rotator 213, the transfer conveyor 214, and the conveyor belt 215, respectively.

The frame 227, the roller 228, and the support member 229 have the same configurations as the frame 217, the roller 218, and the support member 229, respectively.

Fig. 3 is a block diagram showing a functional configuration of the article transport apparatus according to the embodiment.

The article transport apparatus 100 includes a controller 300, a primary side fixed-object group 120, a power source 130, a position sensor 140, and a first transport carriage 210. The position sensor 140 and the secondary movable element 211 of the first conveyance carriage 210 constitute a position detection system 150.

The primary-side fixed element group 120, the power source 130, the position sensor 140, and the first conveyance carriage 210 (the second conveyance carriage 220) are explained with reference to fig. 1 and 2, and therefore, the explanation thereof is omitted. In other words, here, the controller 300 is explained.

The controller 300 controls the operation of the ground primary linear motor system including the primary fixed element group 120 and the secondary movable element 211 of the first conveyance carriage 210. The controller 300 transfers articles to and from the transport device 400 via the transfer units 212 and 222, for example, in a state where the first transport carriage 210 and the second transport carriage 220 are stopped at the transfer section a11, respectively.

The controller 300 may control the primary-side fixed-element group 120 to cause the first conveyance carriage 210 and the second conveyance carriage 220 to travel in synchronization with each other.

The controller 300 is configured by, for example, a processor for executing a predetermined program, a memory for storing a predetermined program, and the like. The controller 300 may be configured by a dedicated circuit.

[ constitution of position detecting System ]

Next, the configuration of the position detection system 150 will be explained.

Fig. 4 is a schematic diagram showing an example of the configuration of the position detection system according to the embodiment.

Fig. 4 shows the relationship between the secondary movable member 211 and the position sensor 140.

The secondary movable element 211 is constituted by two rows of magnet rows 510 and 520. The two- row magnet rows 510, 520 are each composed of a plurality of magnets 511 to 514, 521 to 524 that are arranged repeatedly in a periodic manner with the arrangement pattern as one cycle in the X-axis direction, which is the traveling direction. The magnet row 510 has an arrangement pattern in which four magnets 511 to 514 are arranged in this order as one cycle, and the arrangement pattern is repeated for a plurality of cycles. Similarly to the magnet array 510, the magnet array 520 is also repeatedly arranged for a plurality of periods with one period being an arrangement pattern in which four magnets 521 to 524 are sequentially arranged. Thus, in the arrangement pattern in which the four magnets 511 to 514 are arranged, the width of the arrangement pattern in the X-axis direction is the distance L1 of one cycle. The arrangement pattern of the two magnet rows 510 and 520 is, for example, a halbach arrangement as shown in fig. 4.

In the two rows of magnet rows 510 and 520, the magnets of one magnet row 510 and the magnets of the other magnet row 520 face each other at an arbitrary position in the X-axis direction with surfaces having different polarities. For example, the surface of the N pole of the magnet 511 of the magnet array 510 and the surface of the S pole of the magnet 521 of the magnet array 520 face each other in the Z-axis direction. The surface of the S pole of the magnet 513 of the magnet row 510 and the surface of the N pole of the magnet 523 of the magnet row 520 face each other in the Z-axis direction. In this way, since the magnet rows 510 and 520 in the two rows have the surfaces of different polarities facing each other at a specific position in the X-axis direction, the magnetic flux lines (or magnetic lines of force) extend almost straight from the N pole to the S pole as indicated by open arrows D1 to D2 in fig. 4.

By configuring the two magnet rows 510 and 520 in the halbach array in this way, the magnetic flux density in the Z-axis direction of the space between the two magnet rows 510 and 520 becomes, for example, a distribution of the magnetic flux density waveform shown in fig. 5.

Fig. 5 is a magnetic flux density waveform showing a magnetic flux density distribution in the X-axis direction in the space between two rows of magnets.

As shown in fig. 5, it is understood that in the space between the two rows of magnet rows 510 and 520, the magnetic flux density in the Z-axis direction changes periodically depending on the position in the X-axis direction. One period of the magnetic flux density coincides with the distance L1. Since the magnitude of the magnetic flux density varies depending on the position in the X-axis direction in this way, the position in the X-axis direction of the magnetic sensor 600, which will be described later, can be detected by detecting the magnetic flux density. Note that, when the magnetic flux density is detected only at one point in the X axis direction, the same magnetic flux density may be detected at two different points, and the magnetic sensor 600 may detect the magnetic flux density at two points separated by 1/4 cycles in the waveform of the magnetic flux density, for example. Thus, the magnetic sensor 600 can detect the relative position of the magnetic sensor 600 in the X-axis direction with respect to the two magnet rows 510 and 520.

Further, the relative position of the magnetic sensor 600 with respect to the two rows of magnet rows 510, 520 in the X-axis direction may be calculated based on the position of one of the two detection elements of the magnetic sensor 600 and the position of the zero crossing of the magnetic flux density distribution of the two rows of magnet rows 510, 520. The relative position is, for example, a distance from a position of a zero crossing of the magnetic flux density distribution to a position of the one detection element. The relative position may include a direction from a position of a zero crossing of the magnetic flux density distribution toward a position of the one detection element. The reference position of the magnetic sensor 600 is not limited to the above, and may be a position shifted from the zero-crossing position of the magnetic flux density distribution by a half-cycle phase, for example. The reference positions of the two rows of magnet rows 510 and 520 are not limited to the above, and positions distant from the two detection elements by a predetermined distance may be used as the reference positions.

By storing in advance in the memory the relationship information indicating the relationship between the position and the detection result, which is the detection result when one of the two detection elements of the magnetic sensor 600 is at each position in the X-axis direction of the two rows of magnet rows 510, 520, the relative position of the magnetic sensor 600 with respect to the two rows of magnet rows 510, 520 can be easily calculated from the detection result.

The relationship information may be, for example, a relationship shown in formula 1 below.

Position (L1/2 pi) × θ a (formula 1)

Here, L1 represents the length of one period of the array pattern, and θ a represents an average electrical phase angle described later.

The relationship information is not limited to the above relational expression as long as it is information indicating the relationship between the position and the magnetic flux density, and may be, for example, a table, a graph, or the like, or may be a detection result corresponding to a position obtained by calibration in advance.

The position sensor 140 is disposed between the two rows of magnet rows 510 and 520, and includes a magnetic sensor 600 whose relative position with respect to the two rows of magnet rows in the X-axis direction can be changed. Specifically, the position sensor 140 includes a first detection element 601, a second detection element 602, a third detection element 603, and a fourth detection element 604. The detection elements 601 to 604 are elements for detecting the magnetic flux density in the Z-axis direction. The detection elements 601 to 604 are formed of, for example, hall elements, coils, and the like. When the detection elements 601 to 604 are formed of hall elements, the detection surfaces of the hall elements are arranged in a direction facing one of the magnet rows 510. When the detection elements 601 to 604 are formed of coils, the axes of the coils are arranged in a direction perpendicular to the two rows of magnet rows 510 and 520.

The first detecting element 601 and the second detecting element 602 are separated from each other by a distance L2 of 1/4 cycles of the arrangement pattern in the X-axis direction. In other words, the second detection element 602 is disposed at a position distant from the first detection element 601 in the positive X-axis direction by a distance L2. The distance L2 is 1/4 cycles of the arrangement pattern, and therefore is 1/4 of the distance L1.

The third detecting element 603 is disposed at a position distant from the first detecting element 601 in the positive X-axis direction by a distance L3 of 1/8 cycles of the array pattern. In the present embodiment, the third detection element 603 is disposed between the first detection element 601 and the second detection element 602. The distance L3 is 1/8 cycles of the arrangement pattern, and therefore is 1/2 of the distance L2. In other words, the third detecting element 603 is disposed at a position right in the middle of the position where the first detecting element 601 is disposed and the position where the second detecting element 602 is disposed.

The fourth detecting element 604 is disposed at a position distant from the third detecting element 603 in the positive X-axis direction by a distance L4 of 1/4 cycles of the array pattern. Thus, the distance L4 is equal to the distance L2. Since the two sets of detection elements separated by the same distance are arranged at positions 1/2 offset by the distance, the first to fourth detection elements 601 to 604 are arranged at equal intervals of 1/8 cycles of the predetermined array pattern. Further, the order of arrangement is the order of the first detecting element 601, the third detecting element 603, the second detecting element 602, and the fourth detecting element 604 from the X-axis negative direction side.

The position sensor 140 detects the relative position of the position sensor 140 with respect to the two magnet rows 510, 520 using the detection results of the first to fourth detection elements 601 to 604. In other words, the position sensor 140 performs processing for calculating the relative positions of the position sensor 140 with respect to the two magnet rows 510 and 520 based on the detection results of the first to fourth detection elements 601 to 604. A configuration for executing the above-described processing performed by the position sensor 140 will be described with reference to fig. 6.

Fig. 6 is a block diagram showing an example of a functional configuration of the position sensor.

As shown in fig. 6, the position sensor 140 functionally includes first to fourth detection elements 601 to 604 and a determination unit 141. The determination unit 141 determines the position of the magnetic sensor 600 in the X-axis direction with respect to the two magnet rows 510, 520 based on the detection values of the first to fourth detection elements 601 to 604 as the magnetic sensor 600.

The determination unit 141 obtains, for example, a first voltage indicating a first magnetic flux density from the first detection element 601, and a second voltage indicating a second magnetic flux density from the second detection element 602. Then, the determination unit 141 calculates the first ratio R1 by obtaining the ratio between the acquired first voltage and second voltage, and calculates the first electric phase angle θ 12 by calculating the arctangent of the calculated first ratio R1.

The determination unit 141 obtains, for example, a third voltage indicating the third magnetic flux density from the third detection element 603, and obtains a fourth voltage indicating the fourth magnetic flux density from the fourth detection element 604. Then, the determination unit 141 calculates the second ratio R2 by obtaining the ratio of the acquired third voltage and fourth voltage, and calculates the second electric phase angle θ 34 by calculating the arctangent of the calculated second ratio R2.

Next, the determination unit 141 calculates an average electrical phase angle θ a, which is an arithmetic mean of the calculated first electrical phase angle θ 12 and the calculated second electrical phase angle θ 34. Then, the determination unit 141 determines, as the position of the magnetic sensor 600, the position associated with the calculated average electrical phase angle θ a in the relationship information, using the calculated average electrical phase angle θ a and the relationship information indicating the relationship between the average electrical phase angle and the position.

The determination unit 141 may repeat the above-described position determination process at a predetermined sampling cycle, and perform a count process such as a self-increment of 1 every time one array pattern is moved. Thus, even when the magnetic sensor 600 is positioned in the second and subsequent arrangement patterns of the two rows of magnet rows 510 and 520, the position can be specified as the position in the several arrangement patterns by referring to the counted number.

The determination unit 141 is configured by, for example, a processor that executes a predetermined program, a memory that stores a predetermined program, and the like. The determination unit 141 may be formed of a dedicated circuit. The controller 300 may have the function of the determination unit 141.

[ operation of position detecting System ]

Next, the operation of the position detection system will be described.

Fig. 7 is a flowchart showing an example of the operation of the position detection system.

In the position detection system 150, the first to fourth detection elements 601 to 604 detect the first to fourth magnetic flux densities (S1).

Next, the determination unit 141 calculates the first ratio R1 and the second ratio R2 using the first to fourth magnetic flux densities (S2).

Next, the determination unit 141 calculates the first electrical phase angle θ 12 and the second electrical phase angle θ 34 (S3).

Note that, the methods of calculating the first ratio R1 and the second ratio R2, and the specific methods of calculating the first electrical phase angle θ 12 and the second electrical phase angle θ 34 are as described above, and therefore, detailed description thereof is omitted.

Then, the determination part 141 calculates an average electrical phase angle θ a by calculating an arithmetic mean of the first electrical phase angle θ and the second electrical phase angle θ 34 (S4).

Finally, the determination unit 141 determines the position associated with the average electrical phase angle θ a in the relationship information as the position of the magnetic sensor 600, that is, the position of the position sensor 140 (S5). Thus, the position sensor 140 can detect the position of the first conveyance carriage 210 with respect to the two magnet rows 510 and 520.

[ Effect and the like ]

The position detection system 150 of the present embodiment detects the position of the magnetic sensor 600 with respect to the magnet row. The position detection system 150 includes two rows of magnet rows 510 and 520, a magnetic sensor 600, and a determination unit 141. The two- row magnet rows 510 and 520 are formed of a plurality of magnets that are periodically and repeatedly arranged in the X-axis direction, which is the traveling direction, with a predetermined arrangement pattern as one cycle. The magnets of the two magnet rows 510, 520 face each other at a specific position in the X-axis direction, and the magnets of one magnet row 510 and the magnets of the other magnet row 520 have different polarities. The magnetic sensor 600 is disposed between the two rows of magnet rows 510 and 520, and is disposed so as to be movable relative to the two rows of magnet rows 510 and 520 in the X-axis direction. The determination unit 141 determines the position of the magnetic sensor 600 in the X-axis direction with respect to the two magnet rows 510 and 520 based on the detection value of the magnetic sensor 600. The magnetic sensor 600 has a first detection element 601 that detects magnetic flux density, and a second detection element 602. The second detection element 602 is disposed at a position distant from the first detection element 601 in the X-axis direction by a distance L2 equal to 1/4 cycles of the predetermined array pattern. The determination unit 141 calculates the first electrical phase angle θ 12 by calculating the arctangent of the first ratio R1 of the first magnetic flux density detected by the first detection element 601 and the second magnetic flux density detected by the second detection element 602. Next, the determination unit 141 determines the position of the magnetic sensor 600 using the calculated first electrical phase angle θ 12.

In this way, the position detection system 150 calculates the first electrical phase angle θ 12 using the first magnetic flux density and the second magnetic flux density detected by the first detection element 601 and the second detection element 602 arranged at a position distant from the first detection element 601 in the X-axis direction by a distance L2 of 1/4 cycles of the predetermined array pattern, and determines a position corresponding to the calculated first electrical phase angle θ 12. Therefore, even in the position detection system 150 having two rows of the magnet rows 510 and 520 arranged such that the opposite poles face each other at a specific position, it is possible to effectively detect a change in magnetic flux density between the two rows of the magnet rows 510 and 520 according to the position in the X-axis direction. Thus, the magnetic sensor 600 can appropriately detect the relative position of the magnetic sensor 600 in the X-axis direction with respect to the two magnet rows 510 and 520, based on the values of the magnetic flux densities at the two points detected by the first detection element 601 and the second detection element 602.

Here, fig. 8 is a diagram showing a result of performing fast fourier transform on the magnetic flux density waveform of fig. 5.

As shown in fig. 8, it is understood that the components of the triple wave and the quintuple wave of the fundamental wave are large in the magnetic fields formed by the two rows of magnet rows 510 and 520. As a result, the magnetic field includes a periodic error such as a triple wave or a quintuple wave in addition to the fundamental wave, and there is another problem that a detection error is caused. Therefore, the inventors have provided an error detection element as follows in order to reduce the cycle error.

In the position detection system 150, the magnetic sensor 600 further includes a third detection element 603 and a fourth detection element 604 as error detection elements, which are disposed at positions distant from the first detection element 601 or the second detection element 602 by a distance L3 of 1/8 cycles of the predetermined array pattern. In this way, since the position detection system 150 includes the error detection element, it is possible to reduce an error in the relative position of the magnetic sensor 600 in the X-axis direction with respect to the two rows of magnet rows 510 and 520, which is obtained using the detection results of the first detection element 601 and the second detection element 602.

Specifically, in the position detection system 150, the error detection element includes a third detection element 603 and a fourth detection element 604 for detecting the magnetic flux density. The third detecting element 603 is disposed between the first detecting element 601 and the second detecting element 602, and is disposed at a position distant from the first detecting element 601 in the X-axis direction by a distance L3 of 1/8 cycles of the predetermined array pattern. The fourth detection element 604 is disposed at a position distant from the third detection element 603 toward the second detection element 602 by a distance L4 equal to 1/4 cycles of the predetermined array pattern. The determination unit 141 also calculates a second electric phase angle θ 34 using a second ratio R2 of the third magnetic flux density detected by the third detection element 603 and the fourth magnetic flux density detected by the fourth detection element. Then, the determination unit 141 calculates the average electrical phase angle θ a by obtaining the arithmetic mean of the first electrical phase angle θ 12 and the second electrical phase angle θ 34. The determination unit 141 determines, as the position of the magnetic sensor 600, a position in the relationship information that corresponds to the calculated average electrical phase angle, using the calculated average electrical phase angle θ a and relationship information indicating the relationship between the average electrical phase angle and the position.

Accordingly, in the position detection system 150, an arithmetic mean with the first electrical phase angle θ 12 is calculated using the second electrical phase angle θ 34 obtained by providing the third detection element 603 and the fourth detection element 604, and the position of the magnetic sensor 600 is determined from the average electrical phase angle θ a obtained by the calculated arithmetic mean.

Fig. 9 is a diagram showing a position detection error of a position calculated using each of the first and second electrical phase angles and a position detection error of a position calculated using the average electrical phase angle. The position detection error is a difference between the position calculated using each electrical phase angle and the actual position of the position sensor 140.

As shown in fig. 9, it is understood that the position detection error of the position calculated using the average electrical phase angle is reduced in error compared with the position detection error of the position calculated using each of the first and second electrical phase angles.

By obtaining the average electrical phase angle θ a obtained by the arithmetic average of the first electrical phase angle θ 12 and the second electrical phase angle θ 34 detected at the position separated by 1/4 cycles in this manner, the harmonic components of the triple wave and the quintuple wave can be eliminated. Therefore, the cycle error of the magnetic fields of the two rows of magnet rows 510 and 520 can be reduced, and the position of the magnetic sensor 600 can be determined with high accuracy.

In the position detection system 150, the predetermined arrangement pattern of the two magnet rows 510 and 520 is a halbach arrangement. Therefore, magnetic flux can be concentrated between the two magnet rows 510 and 520.

In the position detection system 150, each of the first detection element 601 and the second detection element 602 may be a hall element and may be arranged in a direction in which the detection surface faces one of the magnet rows 510. In this case, the first detection element 601 and the second detection element 602 can efficiently detect the magnetic flux density in the Z-axis direction.

In the position detection system 150, the first detection element 601 and the second detection element 602 may be coils, respectively, and may be arranged in a direction in which the axis of the coil is perpendicular to the two rows of magnet rows 510 and 520. In this case, the first detection element 601 and the second detection element 602 can efficiently obtain the Z-axis magnetic flux density.

The article transport apparatus 100 as the travel system includes a position detection system 150, a first transport carriage 210 as a travel carriage that is driven by a linear motor having two rows of magnet rows 510 and 520 as a movable element, and a controller 300 that controls travel of the first transport carriage 210 by driving the linear motor in accordance with the position of the magnetic sensor 600 detected by the position detection system 150.

In this way, the two rows of magnet rows 510 and 520 used as the movable elements of the linear motor for driving the first conveyance carriage 210 can be used in the position detection system 150 for detecting the position of the first conveyance carriage 210. Therefore, the manufacturing cost can be reduced. Further, since the two magnet arrays 510 and 520 are in the halbach arrangement, the linear motor can efficiently obtain a driving force by electromagnetic induction.

[ modified examples ]

In the position detection system 150 of the above embodiment, the first detection element 601 and the second detection element 602 are distant from the 1/4-cycle distance L2 of the array pattern in the positive X-axis direction, but the present invention is not limited thereto. The first and second detecting elements 601 and 602 may be separated from each other in the X-axis direction by a distance of (2A +1)/4 cycles (a is an integer of 0 or more) of the array pattern, and may be separated from each other by a distance of 3/4 cycles of the array pattern or 5/4 cycles, for example.

In the position detection system 150 of the above embodiment, the third detection element 603 is disposed at a position distant from the first detection element 601 in the positive X-axis direction by the distance L3 of 1/8 cycles of the array pattern, but the present invention is not limited thereto. The third detecting element 603 may be distant from the first detecting element 601 in the positive X-axis direction by a distance of (4B +1)/8 cycles (B is an integer of 0 or more) of the array pattern, and may be distant from 5/8 cycles of the array pattern, or may be distant from 9/8 cycles, for example.

In the position detection system 150 of the above embodiment, the fourth detection element 604 is disposed at a position distant from the third detection element 603 in the positive X-axis direction by the distance L4 of 1/4 cycles of the array pattern, but the present invention is not limited thereto. The fourth detection element 604 may be distant from the third detection element 603 in the positive X-axis direction by a distance of (2C +1)/4 cycles (C is an integer of 0 or more) of the array pattern, and may be distant from 3/4 cycles of the array pattern, or may be distant from 5/4 cycles, for example.

The position detection system 150 of the above embodiment is configured to include the third detection element 603 and the fourth detection element 604 as the error detection elements, but may be configured not to include the error detection elements.

In this case, the determination unit 141 determines, as the position of the magnetic sensor 600, the position associated with the first electrical phase angle θ 12 in the relationship information, using the calculated first electrical phase angle θ 12 and the relationship information indicating the relationship between the first electrical phase angle θ 12 and the position. In this way, even in a configuration in which the magnetic sensor 600 includes only the first detection element 601 and the second detection element 602, the position of the magnetic sensor 600 can be detected.

The position detection system 150 of the above embodiment uses two detection elements 603 and 604 as error detection elements, but the first electrical phase angle θ 12 calculated from the detection results of the first detection element 601 and the second detection element 602 may be corrected by using one detection element.

In the position detection system 150 of the above embodiment, the arrangement pattern of the two magnet rows 510 and 520 is a halbach arrangement, but the present invention is not limited thereto. For example, one of the two rows of magnet rows may be arranged so that the N-pole and the S-pole are alternately repeated for each magnet or for each plurality of magnets, and the other magnet row may be arranged so that the other magnet row faces the one magnet row at a different magnetic pole.

Fig. 10 is a schematic diagram showing an example of the configuration of a position detection system according to a modification.

In the position detection system 150a, the secondary movable element 211a has two magnet rows 510a and 520 a. The magnet row 510a has a plurality of cycles, with the magnet 511a having the N-pole facing the magnet row 520a and the magnet 512a having the S-pole facing the magnet row 520a as one cycle. Similarly, the magnet row 520a has a plurality of cycles in which the magnet 521a having the S-pole facing the magnet row 510a and the magnet 522a having the N-pole facing the magnet row 510a are arranged in one cycle. The surface of the N pole of the magnet 511a of the magnet row 510a and the surface of the S pole of the magnet 521a of the magnet row 520a face each other in the Z-axis direction. In this way, since the surfaces of the two rows of magnets 510a, 520a having different polarities face each other at a specific position in the X-axis direction, the magnetic flux lines (or magnetic flux lines) extend almost straight from the N-pole toward the S-pole as indicated by hollow arrows D11, D12 in fig. 10.

Although the article transport apparatus 100 of the above embodiment is a floor-based primary linear motor system, it may be realized by a floor-based secondary linear motor system. That is, the magnet arrays 510 and 520 may be disposed on the fixed member side, and the magnetic sensor 600 may be disposed on the movable member side. In this case, the magnet arrays 510 and 520 are fixed parts of the linear motor.

The article transport device according to one or more embodiments of the present invention has been described above based on the embodiments, but the present invention is not limited to the embodiments. The present invention is not limited to the embodiments described above, and various modifications and combinations of the components described in the embodiments may be made without departing from the spirit of the present invention.

The present invention is useful as a position detection system, a travel system, and the like that can appropriately detect the position of a magnetic sensor with respect to two rows of magnet rows when the magnetic sensor is disposed at a position between two rows of magnet rows arranged with specific position opposite poles facing each other.

Description of the reference numerals

10 … article; 100 … article conveying means; 110 … running rails; 120 … primary side set of fixation elements; 130 … power source; 131 … primary side fixing member; 140 … position sensor; 141 … determination part; 150. 150a … position detection system; 210 … a first transport trolley; 211. 211a, 221 … secondary side movable element; 212. 222 … transfer unit; 213. 223 … secondary side rotating member; 214. 224 … transfer conveyor; 215. 225 … conveyor belt; 217. 227 … rack; 218. 228 … roller; 219. 229 … support members; 220 … second conveying trolley; a 300 … controller; 400 … conveying device; 510. 510a, 520a … magnet arrays; 511-514, 511a, 512a, 521-524, 521a and 522a … magnets; 600 … magnetic sensor; 601 … a first detection element; 602 … second sensing element; 603 … third detection element; 604 … fourth detecting element.