JP4438736B2 - Transport device - Google Patents

Description

  The present invention relates to a transport device such as a stacker crane or an overhead traveling vehicle, and more particularly to detecting data error of a target stop position and correcting the data of the target stop position.

Since transport devices such as stacker cranes, overhead traveling vehicles, tracked carriages, and automatic guided vehicles have many stop positions, it is necessary to teach stop data for each stop position in advance when the device is installed. Such teaching is called initial teaching, and initial teaching is difficult because it needs to be performed for each of a large number of stop positions. Patent Document 1 discloses initial teaching as a method of initial teaching by providing a mark on each shelf of an automatic warehouse, recognizing with a sensor of a stacker crane, and obtaining an error of a stop position.
JP-A-3-267206

An object of the present invention is to automatically correct the data of the target stop position without being affected by the change on the stop position side, the wear of the wheels of the transfer device, and the like while the article is being transferred.
An additional problem in the invention of claim 2 is that it is possible to stop according to the data of the target stop position accurately and to increase the reliability when detecting the error of the data of the target stop position.
An additional object of the present invention is to more accurately determine the error of the target stop position data.

This invention stops in accordance with the target stop position data stored in advance with respect to the stop position, and stops at the stop position during the actual conveyance of the article in the conveyance device that delivers the article. For example, every time when the vehicle stops at the stop position, the detection means for detecting the mark provided on the stop position side, the means for determining the error of the data of the target stop position from the data of the detection means, and the obtained error Correspondingly Rutotomoni provided a correcting means for correcting the data of the target stop position from the next time, by providing a withdrawal to transfer means for transferring the article out between the stop position, by the movable mounting means The detection means is installed, and the mark is detected in a state where the transfer means is advanced to the stop position side .

  Preferably, in order to detect an absolute position based on the stop position, a linear sensor whose output is linear and whose output is not skipped like a comb sensor is provided, and the stop position is set by the fully closed stop control by the linear sensor. Stop.

  More preferably, there are provided integration means for integrating the obtained errors and maintenance request means for requesting maintenance when the integration error exceeds a predetermined value.

  In this invention, the data of the target stop position can be corrected without being affected by the change in the stop position side or the wear of the traveling wheels of the transfer device, and the target stop position data is corrected in the process of actually transporting the article. it can. Furthermore, since the data at the target stop position can be repeatedly corrected, it is possible to reliably converge toward the correct data. For this reason, if the data of the target stop position is deviated from the actual due to the change of the stop position side or the conveyance device side, this can be corrected during the conveyance of the article, and the correct target stop position data can be obtained continuously.

  In the second aspect of the invention, since the stop is performed according to the data of the target stop position by the fully closed control using the linear sensor, the stop is performed more accurately and the reliability of the data error of the target stop position is also increased.

In this invention , since the mark is detected in a state where the transfer means is advanced and the distance from the mark is shortened, the error in the data of the target stop position can be detected more accurately, or the mark can be detected by a cheaper sensor. .

In the invention of claim 3 , inspection and repair can be carried out at appropriate timing, and it is possible to prevent the apparatus from being stopped due to a failure.

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

  1 to 6 show an embodiment and its modifications. 1-4, 2 is a stacker crane and 4 is a running rail. Reference numeral 6 denotes a detection plate fixed to the ground side, for example, a magnetic plate. Although the detected plate 6 is shown in the vicinity of the traveling rail 4 in the figure, it may be provided at the bottom of a rack (not shown), and the detected plate 6 is arranged at intervals for each target position in the traveling direction. An ABS linear sensor 8 includes a plurality of coils (not shown), and detects the absolute position of the stacker crane 2 in the horizontal direction with reference to the plate 6 to be detected by changing the magnetic coupling with the plate 6 to be detected. To do. Although the ABS linear sensor 8 can detect the absolute position with respect to the detected plate 6, a plurality of detected plates 6 are provided so that the position cannot be detected at a position where the plate 6 is not present. Further, instead of the ABS linear sensor 8, any sensor that detects a position based on the target stop position can be used.

  10 is a carriage, 12 is a traveling motor, and 14 is a traveling wheel. The number of rotations of the traveling motor 12 and the traveling wheel 14 is monitored by an encoder (not shown), and the traveling distance is calculated. Reference numeral 16 denotes a mast, in which a plurality of detected plates 7 are arranged according to the height positions of a plurality of shelves arranged along the height direction of a rack (not shown). The plate 7 to be detected is detected by the ABS linear sensor 9 provided on the lifting platform 22, and the lifting platform is stopped at the target height position stored for each shelf. The plate 7 to be detected is provided in a jumping manner, and the ABS linear sensor 9 detects an absolute position with reference to each plate 7 to be detected. 18 is a lifting motor, 20 is a suspension material such as a belt, wire, or rope, 22 is the lifting platform, and a slide fork 24 as an example of transfer means is provided, and a mark using an image sensor or the like at the tip thereof A sensor 26 is provided. The travel motor 12 and the lift motor 18 are not limited to rotary motors, and may be linear motors or actuators such as servo cylinders.

  As shown in FIG. 2, the slide fork 24 has both left and right sides, a pair of mark sensors 26 and 27 are provided at both left and right ends, and a rack is provided at the left and right of the traveling rail 4. Here, the rack 30 on the right side of the traveling rail 4 is partially shown, 32 is its column, 34 is a shelf holder, and a mark 36 is provided at the tip of the shelf receiver 34 near the traveling rail 4. Then, the slide fork 24 is advanced to the rack 30 side to reduce the distance from the mark 36, and the mark 36 is detected by the mark sensors 26 and 27.

  3, the mark of the target area 40 is provided at the center of the mark 36, and for example, two concentric circles 41 and 42 are provided around the mark. 43 is the center of the visual field of the mark sensor 26, and the mark sensor 26 evaluates the stop position error from the position of the mark 36 where the visual field center 43 is located. That is, if the visual field center 43 is within the target area 40, it stops at the correct stop position. If it is between the concentric circle 41 and the target area 40, the error is at the first level, and if it is between the concentric circles 41, 42, the error is at the second level. It is. If it is outside the concentric circle 42, the error is at a retry level, the slide fork 24 is returned, the stacker crane is moved to a known position, re-runs toward the same shelf, and is retried.

  When the error level is found, the direction of the error is found from which direction the target area 40 is seen with respect to the visual field center 43. 44 and 45 are boundary lines that divide the mark 36 into four quadrants. When the visual field center 43 is between the concentric circle 41 and the target area 40 at the stop position, the data of the travel target position or the lift target position is corrected by one unit according to which quadrant the visual field center 43 is in. Similarly, between the concentric circle 41 and the concentric circle 42, the data of the travel target position or the lift target position is corrected by 2 units according to which quadrant it is. Any mark shape or mark sensor may be used as long as it can detect an error in the stop position in the traveling direction and the elevation direction and has a resolution corresponding to the required positioning accuracy. Further, the correction method may be such that the error detected in the travel target position or the lift target position is adjusted as it is.

  The encoder 46 monitors the rotational speed of the traveling motor 12 or the rotational speed of the traveling wheel, and inputs the traveling distance to the traveling target position storage unit 48. The travel target position storage unit 48 stores the position for each target stop position such as a shelf or a station, and corrects the position for each stop position. The ABS linear sensor 8 detects an absolute position with reference to the detected plate 6 and inputs it to the travel target position storage unit 48. In this way, the traveling drive unit 52 is configured. In the lift drive unit 54, the number of rotations of the lift motor 18 or the lift distance along the mast 16 is detected by the encoder 47 and input to the lift target position storage unit 50. The ABS linear sensor 9 detects an absolute position with reference to the detected plate 7 and inputs it to the lift target position storage unit 50. Similarly, the lift target position storage unit 50 stores the position for each target stop position such as a shelf or a station, and corrects the position for each stop position.

  An on-machine controller 56 controls the drive units 52 and 54 and corrects the target positions of the target position storage units 48 and 50 according to the error level obtained by the mark sensor 26. Further, the error level obtained by the mark sensor is integrated by the integration unit 58, and is added when the stop position is shifted to the right or up with respect to the target area 40 in the integration. Subtract if shifted down. Therefore, when the visual field center 43 at the time of stop is randomly distributed in the vicinity of the target area 40, the absolute value of the integrated value is a small value. When the absolute value of the integrated value exceeds a predetermined value, an alarm is issued from the on-board controller (maintenance request means) 56 to request maintenance of the stacker crane or rack. For example, when the visual field center 43 at the stop position is a retry level outside the concentric circle 42 of the mark 36, a large number such as 5 is added to or subtracted from the integrating unit 58 according to the error direction. When the absolute value of the integrated value of the integrating unit 58 is 10 or more, for example, maintenance is requested. This is a case where maintenance of the control system is necessary because the operation could not be stopped within the allowable range twice or more, or maintenance is necessary because errors are accumulated in the same direction. It should be noted that since the data of the target stop position is unstable within a predetermined period from the start of operation of the stacker crane 2, the accumulation by the integrating unit 58 is not performed.

  In addition, when the embodiment is applied to an overhead traveling vehicle or the like instead of a stacker crane, a lateral feed portion 60 indicated by a chain line in FIG. 3 is provided. Reference numeral 62 denotes a lateral feed motor, and reference numeral 64 denotes an encoder, which obtains the lateral feed distance of the lateral feed motor. Further, the ABS linear sensor 66 obtains the lateral feed distance based on the detected plate 68 provided in the overhead traveling vehicle, and inputs it to the lateral feed target position storage unit 70. When the lateral feed stroke is short and the entire lateral feed stroke can be monitored by the ABS linear sensor 66, the encoder 64 is unnecessary.

  The operation of the embodiment is shown in FIG. When travel target positions such as rack shelves and loading / unloading stations are given, the remaining travel distance and remaining lift distance are calculated by the encoder, and the target function of the travel command is created according to these and the stacker crane is used for feedback control. Run and move up and down. When entering the section in which the ABS linear sensor can perform stop control, the ABS linear sensor calculates the remaining distance based on the plate to be detected, performs full-closed feedback control, and stops. Next, a transfer means such as a slide fork or a SCARA arm is operated, for example, a mark is recognized using a mark sensor provided at the tip of the transfer means, and the error is evaluated. The stacker crane is already stopped when the mark is recognized by the mark sensor, and the transfer means is operating. It is corrected and used for the next control. Further, the error is integrated by the integration unit, and when the integration error exceeds a predetermined value α, maintenance is requested and the control system, rack, etc. are inspected. When the error is a retry level, the stacker crane is returned to a known position, and the stop to the same target position is retried.

The embodiment has the following characteristics.
1) An approximate target position need only be given initially, and there is no need to teach the correct target position first. This makes it easy to set up an automated warehouse. For example, it is necessary to teach the traveling target position and the lifting target position of the stacker crane with respect to hundreds of shelves accurately, but this can be eliminated.
2) The target position error can be corrected every time it stops at a shelf or loading / unloading station. Here, the error of the target position is corrected every time the vehicle stops, but may be corrected at a rate of once every two times, for example.
3) If the rack is gradually deformed, or if the wheel is worn due to long-term operation of the stacker crane, an error in stop control occurs, it can be corrected by constantly correcting the target position with the mark sensor.
4) Since the same target position can be repeatedly corrected many times, even if the correction amount per time is small, it can be corrected so that it converges to the correct target position. In addition, it is not necessary to stop conveyance and teach in order to correct the secular change, and it can be corrected during actual operation.
5) The error and the correction amount for correcting this may not necessarily correspond to 1: 1. For example, in the case of multi-axis control, particularly when the movement directions of the axes are not orthogonal, the relationship between the error and the correction amount is complicated. However, in the embodiment, if correction smaller than the error is performed so that the error falls within the allowable range and no overcorrection occurs, the control can be performed so that the stop can be performed within the allowable range in any case.

  Although the embodiment has been applied to the stacker crane 2, the type of the transfer device is arbitrary, and may be, for example, an overhead traveling vehicle, a grounded tracked carriage, or an automatic guided vehicle traveling on the ground without a track. The mark sensor is not limited to an image sensor as long as it can detect an error in a stop position with reference to a mark in a plurality of stages. In the embodiment, both the control by the encoder and the control by the ABS linear sensor are performed, but only the stop control by the encoder may be performed.

  Application examples to the overhead traveling vehicle 72 are shown in FIGS. 5 and 6, and the traveling control is the same as that of the stacker crane 2, and the control of the traveling drive unit 52 of FIG. 3 is used. Regarding the lifting control, the load applied to the lifting platform is measured, and when the load suddenly changes, the lifting of the lifting platform is stopped, and when the lifting of the lifting platform is completed, the lifting is terminated. For this reason, the elevation control itself is simple, and position detection and error correction by the ABS linear sensor are not performed for elevation. On the other hand, the lateral feed unit 60 is provided so that articles can be delivered to parts other than directly below the overhead traveling vehicle 72, and the lateral feed direction is controlled and the error is corrected.

  In FIG. 5, reference numeral 72 denotes an overhead traveling vehicle that travels along a traveling rail 74 provided on the ceiling of the clean room, and the traveling rail 74 includes a traveling drive unit (not shown) of the overhead traveling vehicle 72. 76 is an ABS linear sensor, 77 is a plate to be detected such as a magnetic body, and is preferably provided at each stop position, and 78 is a moving body in the lateral feed section, which is substantially perpendicular to the traveling rail 74 in the horizontal plane. It moves and the lateral feed distance is detected by an ABS linear sensor or encoder (not shown). Reference numeral 80 denotes a rotation unit that rotates the elevating drive unit 82 in a horizontal plane. The rotating unit 80 may not be provided. Reference numeral 84 denotes an elevating table, which is moved up and down with respect to the elevating drive unit 82 by a suspension member 86, and chucks an article in the cassette 90 with a chuck 88. Reference numeral 92 denotes a buffer to be delivered, which may be a load port or the like, and is provided with a mark 36 at a predetermined position, and is detected by the mark sensor 26 protruding in the horizontal plane from the lifting platform 22 while lowering the lifting platform 22. Reference numeral 94 denotes a buffer column. FIG. 6 shows an arrangement example of the mark sensor 26 of the lifting platform 84 with respect to the mark 36 of the buffer 92.

5 and 6, the mark sensor 26 can easily recognize the mark 36 by lowering the elevator 84, and the travel target position and the lateral feed target position are corrected according to the error level evaluated at this time. To do. The other points are the same as those of the stacker crane 2.

Side view of main part of stacker crane of embodiment The top view which shows the raising / lowering base of the stacker crane of an Example, and the mark provided in the shelf holder of the rack The block diagram which shows the control system of the conveying apparatus of an Example The flowchart which shows the movement control algorithm in the conveying apparatus of an Example. The figure which shows typically the figure which the overhead traveling vehicle is detecting the mark on a buffer in a modification. The top view which shows the relationship between the raising / lowering platform of an overhead traveling vehicle and the mark on a buffer in FIG.

Explanation of symbols

2 Stacker crane 4 Traveling rails 6, 7 Detected plates 8, 9 ABS linear sensor 10 Car 12 Traveling motor 14 Traveling wheel 16 Mast 18 Lifting motor 20 Lifting material 22 Lifting base 24 Slide fork 26, 27 Mark sensor 30 Rack 32 Column 34 Shelf support 36 Mark 40 Target area 41, 42 Concentric circle 43 Mark sensor visual field center 44, 45 Boundary line 46, 47 Encoder 48, 50 Storage unit 52 Traveling drive unit 54 Elevating drive unit 56 On-board controller 58 Integration unit 60 Horizontal feed Unit 62 transverse feed motor 64 encoder 66, 76 ABS linear sensor 68, 77 detected plate 70 storage unit 72 overhead traveling vehicle 74 traveling rail 78 moving body 80 rotating unit 82 lifting drive unit 84 lifting platform 86 suspension material 88 chuck 90 Cassette 92 Buffer 94 Prop

Claims (3)

In the transfer device that stops according to the data of the target stop position stored in advance with respect to the stop position and delivers the article,
When the article is actually conveyed and when the article is stopped with respect to the stop position during conveyance, the detection means for detecting the mark provided on the stop position side and the error of the data at the target stop position are detected by the data of the detection means. Means for seeking,
Rutotomoni provided a correcting means for correcting the data of the target stop position from the next time in accordance with the obtained error,
In the state where the transfer means for transferring the article by moving to and from the stop position is provided, the detection means is installed in the transfer means, and the transfer means is advanced to the stop position side. A conveying apparatus characterized by detecting a mark . 2. The transport apparatus according to claim 1, wherein a linear sensor for detecting an absolute position with respect to the stop position is provided, and the stop is performed at the stop position by full-closed stop control by the linear sensor. 3. The transport apparatus according to claim 1 , further comprising: an integrating unit that integrates the obtained error; and a maintenance request unit that requests maintenance when the integrated error exceeds a predetermined value.

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