JP2007010534A - Movable body system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a movable body system capable of recognizing the position even in the interval of a curve with few affection of noise from the feeder. <P>SOLUTION: The detection plate 14 to be detected keeps the permanent magnets 48 to 50 arranged in the running direction on the rail side. The overhead travelling truck keeps the coils 54 arranged in a running direction. The linear sensor 12 provided with the optical sensors 51 to 53 is made to oppose to the detection plate 14 in vertical direction. The optical sensors 51 to 53 discriminate between the linear interval and the curved interval, for changing the effective range of the linear sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a system for determining the position of a moving body.

  Patent Document 1 discloses that a linear sensor in which a plurality of coils are linearly arranged is provided and a relative position between a detected plate made of a ferromagnetic plate or the like and the linear sensor is obtained. When the relative position between the plate to be detected and the linear sensor is called a phase, the magnetic coupling between each coil and the magnetic material changes depending on the phase. Therefore, for example, the position of the linear sensor relative to the plate to be detected can be obtained from the amplitude and phase of the voltages of a plurality of coils connected in series.

The inventor uses this technology to recognize the position of a transport vehicle such as an overhead traveling vehicle, a tracked track truck, a stacker crane, an unmanned transport vehicle that travels on the ground without a track, or a turntable, lifter, head of various machines, etc. We used it for position recognition. By the way, in such applications, it has been found that the surrounding power lines are not particularly shielded in many cases, and the leakage magnetic field becomes an error to the linear sensor. A sufficient shield may be applied to the linear sensor or the plate to be detected against the leakage magnetic field. However, the linear sensor or the plate to be detected is enlarged, and interference with the shield also becomes a problem.
JP 2001-174206 A

An object of the present invention is to improve the S / N ratio of a linear sensor so that it is not easily affected by a peripheral magnetic field and increases the accuracy of position recognition.
An additional problem in the invention of claim 2 is that a tracked carriage traveling along a rail having a power supply line for non-contact power supply can accurately recognize the position in a leakage magnetic field from the power supply line. Is to make it.
An additional problem in the invention of claim 3 is to make it possible to recognize the position even when the moving body is rotating.

  According to the present invention, a plate to be detected including a magnet is disposed along a moving path of a moving body, and a linear sensor in which a plurality of coils are arranged is provided on the moving body, and the magnetic coupling between the coil of the linear sensor and the magnet is provided. In the moving body system, the position with respect to the plate to be detected is obtained from the change in the above.

Preferably, a plurality of magnets are arranged in a straight line, and magnetic yokes are arranged at the front and rear ends of the magnet row in the moving direction of the moving body so as to face the linear sensor.
Preferably, the movable body is a tracked carriage that travels along a rail provided with a power supply line for non-contact power supply and receives power from the power supply line by a pickup coil.

  Preferably, the linear sensor and the plate to be detected are opposed to each other with an interval in a direction perpendicular to the moving surface of the moving body.

  In the present invention, since a detection plate made of a magnet is used, the magnetic coupling with the coil is much stronger than that of a ferromagnetic detection plate such as an iron plate or a nickel plate. For this reason, the S / N ratio with respect to magnetic noise from the surroundings is increased, and the position of the moving body can be accurately recognized even in a noisy environment, for example, without a magnetic shield.

  According to the second aspect of the present invention, the position of the tracked carriage is accurately determined by using the fact that the S / N ratio against magnetic noise from the non-contact power feeding line can be increased by using the magnet for the plate to be detected. Can be recognized.

  In the invention of claim 3, since the plate to be detected and the linear sensor face each other in a direction perpendicular to the moving surface, the plate to be detected and the linear sensor are unlikely to interfere even if the moving body rotates. Therefore, the position can be recognized even when the moving body is in a curve motion.

  In the following, an optimum embodiment for carrying out the present invention will be shown.

  1 to 8 show an embodiment and its modifications. In the figure, reference numeral 2 denotes an overhead traveling vehicle system, which may be a grounded track system, a stacker crane system, or an automatic guided vehicle system that travels on the ground without a track. In the case of a stacker crane, it may be used for position recognition of a traveling carriage, for height recognition of a lifting platform, or for position recognition of a transfer means such as a turn angle of a turntable or a slide fork. In addition, the present invention can be applied to position recognition of various turntables, lifters, machine tool heads, and other various moving bodies.

  4 is a rail, for example, installed along the ceiling space in the clean room, 6 is a straight section, 8 is a curve section, 9a is a curve entrance, and 9b is a curve exit. Reference numeral 10 denotes an overhead traveling vehicle that travels so as to be suspended from the rail 4, for example, and the overhead traveling vehicle main body is provided with a lateral feed portion, a rotating portion in a horizontal plane, a lifting drive portion and a lifting platform. To grip and transport articles such as semiconductor cassettes.

  A linear sensor 12 is provided on the side of the overhead traveling vehicle 10, 14 is a plate to be detected, and is provided on a side of the rail 4. The linear sensor 12 and the plate 14 to be detected are spaced apart in the vertical direction. opposite. The moving surface of the overhead traveling vehicle 10 is horizontal, and if the linear sensor 12 and the plate 14 to be detected are opposed to each other with an interval in the vertical direction, they do not interfere even in the curve section, and therefore the plate 14 to be detected can be installed in the curve section. . Reference numeral 16 denotes a load port, for example, an article carry-in / out entrance of the processing apparatus 18. Here, the stop position of the overhead traveling vehicle 10 is representatively shown by the load port 16.

  The linear sensor and the plate to be detected may be arranged at intervals in the horizontal direction. When such an overhead traveling vehicle is denoted by 10 ', the linear sensor 12' faces a detected plate (not shown) in the horizontal direction, and the opposed surfaces face the vertical direction. If it does in this way, the interference range 13 of linear sensor 12 'will become like the chain line of FIG. 1, and it will be necessary to leave a big space | interval between to-be-detected plate and linear sensor 12'. Therefore, the sensitivity of the linear sensor 12 'is low, and the position cannot be detected in the curve section. For example, it is assumed that the linear sensor 12 ′ is parallel to the traveling rail 4 when the overhead traveling vehicle 10 ′ escapes completely downstream from the curve exit 9 b. Then, the position where the load port 16 or the like of the processing apparatus can be installed is on the downstream side of the chain line 9c in FIG. 1, and a load port or the like cannot be installed in the vicinity of the curve inlet 9a and the curve outlet 9b and the curve section 8. Considering that the clean room space is expensive, this is a significant problem. The arrangement like the linear sensor 12 ′ is not excluded.

  In FIG. 2, reference numeral 22 denotes a travel rail, and reference numeral 24 denotes a lower power supply rail. The detected plate 14 is supported by a bracket 26 on the side of the power supply rail 24. The plate 14 to be detected may be provided on the bottom surface of the power supply rail 24 and the linear sensor 12 may be provided on the top surface of the overhead traveling vehicle main body 44 so as to be opposed to each other in the vertical direction. The travel route 22 is provided with a guide 28 to guide the straight traveling and branching of the overhead traveling vehicle 10, and the traveling unit 31 is provided with, for example, left and right support wheels 32, 32 and an upper central drive wheel 34. Further, guide wheels 36 and 38 are provided and guided by the guide 28. For example, a pair of litz wires 30, 30 are provided on the power supply rail 24, a high-frequency current of about 1 to 10 kHz is passed, and power is received by the pickup coil 40 of the overhead traveling vehicle 10. Communicate with car controllers and other overhead vehicles. Reference numeral 42 denotes a shaft that supports the overhead traveling vehicle main body 44, and the main body 44 is provided with a lateral feed portion, a horizontal rotation portion, a lift drive portion, a lift platform, and the like.

  3 to 7 show the configuration of the linear sensor 12 and the plate 14 to be detected, and the left-pointing arrow in each figure is the traveling direction of the overhead traveling vehicle. Actually, the linear sensor 12 moves relative to the plate 14 to be detected, but in FIG. 3, the position of the linear sensor 12 is fixed and the plate 14 to be detected is shown as moving. In the vicinity of the plate 14 to be detected, the moving surface of the overhead traveling vehicle 10 is horizontal, and the vertical height of the linear sensor 12 and the plate 14 to be detected is constant.

  46 is a ferromagnetic yoke, and 48 to 50 are permanent magnets. For example, a ferrite magnet is used, and a stronger magnet such as a rare earth magnet may be used. An electromagnet may be used instead of the permanent magnet. The magnets 48 to 50 are preferably arranged in a straight line along the traveling direction of the overhead traveling vehicle. Each of the magnets 48 to 50 has a constant size, and the direction of magnetization may be the vertical direction or the traveling direction of the overhead traveling vehicle. And the direction of magnetization is reversed between adjacent magnets. The number of magnets 48 to 50 is preferably 2 or more, and the upper limit is, for example, 16 or less.

  In the linear sensor 12, a plurality of coils 54 are linearly arranged. For example, four coils 54 are set as one set, and about 2 to 16 sets are arranged. Reference numerals 51 to 53 denote optical sensors, which are linearly arranged from the front side (front side in the running direction) to the rear side (back side in the running direction) of the linear sensor 12, and the number thereof is, for example, three. It is detected whether the detection plate 14 exists. In place of the optical sensors 51 to 53, an ultrasonic sensor, a magnetic sensor, or the like may be used.

  When the passing range of the detected plate 14 with respect to the linear sensor 12 is indicated by a chain line 56 in FIG. 3, the optical sensor 51 does not detect the detected plate 14 in the curve section, but the optical sensors 52 and 53 detect the detected plate 14. . Further, in the straight section, each of the optical sensors 51 to 53 detects the detected plate 14 and can discriminate between the curved section and the straight section by the presence or absence of detection by the optical sensor 51. In the straight section, the range L1 in FIG. 3 is the effective range of the linear sensor 12, and in the curve section, the range L2 is the effective section. The linear sensor 12 detects the position in the longitudinal direction, and this does not change even when the overhead traveling vehicle travels in a curve section. Therefore, the linear sensor 12 is not a name of a position sensor or the like but is called a linear sensor.

  As shown in FIGS. 4 and 5, since the height position of the linear sensor 12 and the plate 14 to be detected is constant, the vertical distance between them can be made extremely small, and the magnetic coupling between the coil 54 and the permanent magnets 48 to 50 can be achieved. Can be strong. In addition, the surrounding yoke 46 or the like can limit the intrusion of a magnetic field from a litz wire or the like. As shown in FIG. 5, the magnetic flux from the detection plate 14 leaks to the linear sensor 12 side between the magnets 48 and 50 and the yoke 46 and between the magnets 48 and 49 and between the magnets 49 and 50. As shown in the upper right side of FIG. 5, this does not change even if the magnetization direction in the magnet 48 or the like is the vertical direction, and the magnetization direction is the traveling direction of the rail as in the magnet 48 ′. As the number of magnets 48 to 50 is increased, for example, the number of coils 54 that can be simultaneously used for detection is increased, and the detection accuracy is improved. The magnetic flux leaking to the linear sensor 12 side from the plate 14 to be detected interferes with the magnetic flux of the coil 54, and the magnetic resistance of the coil 54 is changed to enable position detection. The magnetic flux leaking from the permanent magnets 48 to 50 to the linear sensor 12 is sufficiently stronger than the magnetic flux leaking from the litz wire 30, for example, about 10 to 1000 times.

  In the embodiment, since the coils 54 are used as one block in units of four, the phase for each block is defined as shown in FIG. That is, there are four detection coils 54a to 54d in one block, the phase θ is set to 0 at the position where the detected plate 14 appears on the uppermost side of the upstream detection coil 54a, and the detected plate 14 is the last coil. The phase θ is set to 180 ° at the position where it escapes from 54d. While the phase changes from 0 ° to 180 °, the strength and the direction of the magnetic flux received by each of the coils 54a to 54d from the magnets 48 to 50 change, thereby detecting the phase θ.

  FIG. 7 shows an example of a phase θ detection circuit. Reference numeral 60 denotes an AC power supply. For example, one block of coils 54a to 54d is connected in series, and a sin wave current is applied at phase ωt. On the other hand, if the calculation unit 62 processes the absolute value of the voltage of each coil and its phase, for example, sin θ and cos θ can be obtained. Various calculation methods for obtaining positions from the voltages and current phases of a plurality of coils are described in Patent Document 1 and are not limited to those shown in FIG.

  FIG. 8 shows a modified linear sensor 70 and a modified detection target plate 74. In the linear sensor 70, a plurality of coils 72 are linearly arranged above and below the linear sensor 70. In the plate 74 to be detected, a permanent magnet 78 is supported by a yoke 76, and the upper and lower coils 72, 72 are opposed to the upper and lower sides of the permanent magnet 78. In this case, in the curve section, the interference range of the detected plate 74 when the linear sensor 70 is fixed is as shown by 80 in FIG. 8, and the interval between the linear sensor 70 and the detected plate 74 in the horizontal direction. If this is set, interference can be prevented. In contrast to FIG. 8, the plate to be detected may be configured in a gate shape, and the linear sensor may pass through the gap between the gates.

In the embodiment, the following effects can be obtained.
1) Since permanent magnets 48 to 50 are used for the plate to be detected 14 and the like, the magnetic coupling with the coil 54 and the like of the linear sensor 12 is much stronger than in the case of an iron plate or a nickel plate. For this reason, because of the litz wire 30 or the like, the position can be detected with a high S / N ratio even in an environment with strong magnetic noise.
2) Further, along with this, like the linear sensor 12 and the plate 14 to be detected, these opposed portions can be opened, and it is not necessary to shield them. As shown in FIG. 8, the S / N ratio may be further improved by shielding either the linear sensor 70 or the detected plate 74 so as to surround the facing portion.
3) Since the linear sensor 12 and the detected plate 14 are horizontally opposed to each other with a gap in the vertical direction, they do not interfere even when the overhead traveling vehicle 10 travels in a curve.
4) As a result, the distance between the linear sensor 12 and the detected plate 14 can be reduced, and the magnetic coupling can be further increased.
5) The position of the overhead traveling vehicle 10 can be detected not only in the straight section 6 but also in the curved section 8. For this reason, the load port 16 etc. can be arrange | positioned in the curve area 8 and the linear part of the circumference | surroundings, and a clean room can be used effectively.
6) The linear sensors 12 and 70 can detect whether the light sensor 51 to 53 is a straight section or a curve section. For this reason, the effective range of the linear sensors 12 and 70 can be switched accurately.

The principal part top view of the overhead traveling vehicle system of an Example The principal part front view with a partial notch which shows the rail in an Example, to-be-detected plate, and an overhead traveling vehicle The top view which shows a linear sensor and a to-be-detected plate in an Example. Side view showing a linear sensor and a plate to be detected in the embodiment The figure which shows typically the detection coil of the linear sensor in an Example, and the magnetic flux from a to-be-detected plate. The figure which shows the phase of the linear sensor in an Example Block diagram of the linear sensor in the embodiment The figure which shows the linear sensor and to-be-detected plate of a modification

Explanation of symbols

2 Overhead traveling vehicle system 4 Rail 6 Straight section 8 Curve section 9a Curve entrance 9b Curve exit 10 Overhead traveling vehicle 12 Linear sensor 13 Interference range 14 Detected plate 16 Load port 18 Processing device 22 Travel rail 24 Feed rail 26 Bracket 28 Guide 30 Litz wire 31 Traveling portion 32 Support wheel 34 Drive wheel 36, 38 Guide wheel 40 Pickup coil 42 Shaft 44 Ceiling traveling vehicle body 46 Yoke 48-50 Permanent magnets 51-53 Optical sensor 54 Coil 56 Passing range 60 of plate to be detected AC power supply 62 arithmetic unit 70 linear sensor 72 coil 74 detected plate 76 yoke 78 permanent magnet 80 interference range

R Center of curvature L1 Effective range of straight section L2 Effective range of curve section θ Phase

Claims (3)

A detection plate made of a magnet is arranged along the moving path of the moving body, and a linear sensor in which a plurality of coils are arranged is provided on the moving body, and from the change in magnetic coupling between the coil of the linear sensor and the magnet, A mobile system that determines the position relative to the plate to be detected. 2. The mobile system according to claim 1, wherein the mobile body is a tracked carriage that travels along a rail provided with a power supply line for non-contact power supply and receives power from the power supply line by a pickup coil. The moving body system according to claim 1 or 2, wherein the linear sensor and the plate to be detected are opposed to each other with an interval in a direction perpendicular to the moving surface of the moving body.

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