JP2007323111A - Positioning controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positioning controller which can greatly shorten the time needed to preset an encoder without limiting the storage capacity for positioning data. <P>SOLUTION: The positioning controller 20 according to the present invention includes a servo motor 13 which drives a moving body; an incremental type encoder 21 which detects the rotational quantity of the servo motor 13; a servo driver 22 which receives a positioning control signal and a detection signal from the encoder 21 to drive and control the servo motor 13; a laser range finder 23 which measures the position of the moving body on a linear track; and a controller 16 which stores positioning data of the moving body and outputs a positioning control signal to the servo motor 22. The controller 16, after being powered on, presets the encoder 21 by using measurement data from the laser range finder 23 prior to a positioning control operation for the moving body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positioning control device for positioning a moving body (for example, a stacker crane or its carriage) that moves on a straight track at a desired position.

  Conventionally, an automatic warehouse is equipped with a stacker crane 30 for carrying out a transporting operation for putting in and out articles with a storage shelf provided with a large number of storage frames for storing articles. As shown in FIG. 3, the conventional stacker crane 30 has a carriage 33 having a traveling roller 32 and is movably mounted on a traveling rail 34 laid in an automatic warehouse. Although the storage shelves are not shown, the storage shelves are arranged at intervals in positions corresponding to the back side and the near side of the paper surface, and the stacker crane 30 travels between them. The traveling roller 32 is driven by a traveling motor 35 installed on the carriage 33, so that the carriage 33 moves on the traveling rail 34 in the direction of arrow X in the figure. A pair of masts 36, 36 are erected on the carriage 33, and an upper frame 37 is attached to the upper part of the mast 36. A carriage 38 for placing an article is attached along the mast 36 so as to be movable up and down. Sheaves 39, 39 are attached to the upper frame 37, and a wire 42 extending from the winch 41 is stretched over each sheave 39, and a carriage 38 is supported in a suspended state at the tip of the wire 42. The carriage 33 is provided with a lifting motor 43 that drives the winch 41 to rotate forward and backward, and the carriage 38 moves up and down along the mast 36 by the driving of the lifting motor 43.

The carriage 38 is equipped with a fork 44 for loading and unloading articles with respect to the storage frame of the storage shelf. The fork 44 is configured to be movable back and forth in the horizontal direction (vertical direction in FIG. 3) on either side of the storage shelves arranged on both sides of the stacker crane 30. On the other hand, the fork 44 is advanced and retracted in a state where the carriage 38 is opposed to the carriage 38, so that articles can be taken in and out of the storage unit. The fork 44 is driven by a fork motor (not shown).
A guide rail 45 is disposed above the stacker crane 30, and the upper frame 37 is guided along the guide rail 45 when the stacker crane 30 travels.
The stacker crane 30 also includes a control device (PLC) 46 that controls the travel motor 35, the lifting motor 43, and the fork motor.

Prior arts related to such stacker crane positioning control are disclosed in Patent Documents 1 and 2 below.
Japanese Patent Application Laid-Open No. 2004-228561 discloses an apparatus that uses an induction motor as a traveling motor and a lifting motor of a stacker crane, and controls the traveling of the crane and the lifting and lowering of the carriage by inverter control.
In the cited document 2, an AC servo motor is used as a travel motor of the stacker crane, so that the stacker crane can be smoothly stopped at a predetermined position by performing deceleration control until the AC servo motor is stopped without using a brake. Are disclosed.

JP-A-8-202446 JP 7-187320 A

In recent years, shortening the cycle time of automatic warehouse operation has become an important issue. To that end, it is indispensable to quickly and accurately stop the carriage and stop the carriage. As described in the above-mentioned Patent Document 1 and the like, the conventional general stacker crane performs positioning control for running and raising / lowering by performing inverter control of the induction motor. On the other hand, if a positioning control servomotor (hereinafter referred to as a servomotor) is used as a travel motor and a lifting motor as in Patent Document 2, positioning control can be performed quickly and accurately.
In the servo motor, an encoder for detecting the rotation amount is attached in order to perform accurate positioning control. There are absolute encoders that detect absolute positions by counting, and incremental encoders that detect relative positions by counting, but servo motors mainly employ incremental encoders.

  However, in a servo motor that employs an incremental encoder, the absolute position cannot be discriminated when the power is turned on. It is necessary to perform the return to origin operation and preset the encoder. For this reason, when the moving distance of the moving body is long, such as a stacker crane, there is a problem that it takes a long time to preset the encoder. In addition, there is a problem that it is necessary to arrange a detection piece attached to the moving body and an origin sensor for detecting the detection piece.

  In addition, a servo driver for driving and controlling the servo motor is connected to the servo motor. However, since it is necessary to store positioning data in the servo driver, the servo driver has a limited storage capacity. When storing the positioning data, it is necessary to directly teach the positioning position to the servo driver, and it is difficult to monitor the positioning data on the control device side. In addition, the positioning data cannot be corrected easily.

  The present invention has been made in view of the above-described problems, can greatly reduce the time required for encoder presetting, does not require an origin sensor, and limits the storage capacity of positioning data. It is an object of the present invention to provide a positioning control device that can monitor positioning data on the control device side and can easily correct positioning data.

In order to solve the above problems, the positioning control device according to the present invention employs the following means.
(1) That is, a positioning control device according to the present invention is a positioning control device that positions a moving body that moves on a linear track at a desired position, and detects a servo motor that drives the moving body and the amount of rotation of the servo motor. An incremental encoder that performs positioning, a servo driver that receives a positioning control signal and a detection signal from the encoder and controls the servo motor, a laser rangefinder that measures the position of the moving body in the linear track, and the movement And a controller that stores positioning data of the body and outputs a positioning control signal to the servo driver. The controller, after turning on the power, prior to the positioning control operation of the moving body, The encoder is preset using the measurement data from.

As described above, since the positioning control servomotor that positions the moving body by feedback control is employed, positioning control can be performed quickly and accurately.
In addition, since the encoder is preset using the measurement data from the laser distance meter after the power is turned on and prior to the positioning control operation of the moving body, the conventional home position return operation is unnecessary. Therefore, the encoder can be preset in a short time after the power is turned on. Moreover, there is no need to install an origin sensor.
In addition, since the positioning data previously stored in the servo driver is stored in the control device having a large storage capacity, the limitation of the storage capacity can be eliminated and the positioning data can be stored much more. it can.

(2) In the above positioning control device, the control device acquires the stop position of the moving body moved by driving the servo motor with a laser distance meter, and the stop position based on the measurement data of the laser distance meter is the target. When it does not coincide with the stop position, a control signal is output to the servo driver so that the moving body moves to the target stop position based on measurement data from the laser rangefinder.

  In this way, in addition to monitoring the stop position by feedback control of the servo motor, the stop position is also monitored by the laser distance meter, so double stop position monitoring is possible. When the stop position based on the measurement data of the laser distance meter does not coincide with the target stop position, the position of the moving body is corrected based on the measurement data of the laser distance meter, so that highly accurate positioning can be performed.

(3) Further, in the above positioning control device, the control device corrects positioning data based on a deviation amount when the stop position of the moving body does not coincide with the target stop position. .

  Since the positioning data is stored in the control device, the correction can be easily performed. In addition, when the stop position of the moving body does not coincide with the target stop position, the positioning data is corrected based on the deviation amount, so that the next position correction without performing the position correction again. The moving body can be positioned at the target stop position quickly and accurately.

  According to the present invention, the time required for presetting the encoder can be greatly reduced, the origin sensor need not be arranged, the storage capacity of the positioning data is not limited, and the positioning data can be stored on the control device side. It is possible to monitor and to obtain an excellent effect that the positioning data can be easily corrected.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

FIG. 1 is a diagram showing an embodiment in which the positioning control device of the present invention is applied to a carriage of a stacker crane.
The stacker crane 1 has a carriage 3 having a traveling roller 2 and is movably mounted on a traveling rail 4 laid in an automatic warehouse. Here, although the storage shelf is not shown in the figure, the storage shelf is disposed at a position corresponding to the back side and the near side of the paper, with the stacker crane 1 traveling between them.

  The traveling roller 2 is driven by a traveling motor 5 installed on the carriage 3, whereby the carriage 3 moves on the traveling rail 4 in the direction of arrow X in the figure. A pair of masts 6, 6 are erected on the carriage 3, and an upper frame 7 is attached to the upper part of the mast 6. A carriage 8 for placing an article is attached along the mast 6 so as to be movable up and down. Sheaves 9 and 9 are attached to the upper frame 7. A wire 12 extending from the winch 11 is stretched over each sheave 9, and a carriage 8 is supported in a suspended state at the tip of the wire 12. The carriage 3 is provided with an elevating motor 13 that drives the winch 11 to rotate forward and backward, and the carriage 8 moves up and down along the mast 6 by driving the elevating motor 13.

The carriage 8 is equipped with a fork 14 for loading and unloading articles with respect to a storage frame constituting a storage shelf. The fork 14 is configured to be able to advance and retract in the horizontal direction (perpendicular to the plane of FIG. 1) on either side of the storage shelves arranged on both sides of the stacker crane 1, and the storage frame to be used for loading and unloading On the other hand, the fork 14 is advanced and retracted with the carriage 8 facing the carriage 8, so that articles can be taken in and out of the storage unit. The fork 14 is driven by a fork 14 motor (not shown).
A guide rail 15 is disposed above the stacker crane 1, and the upper frame 7 is guided along the guide rail 15 when the stacker crane 1 travels.
The stacker crane 1 also includes a control device 16 that controls the travel motor 5, the lifting motor 13, and the fork motor.

FIG. 2 is a block diagram of the positioning control device 20 according to the present embodiment. The positioning control device 20 is for positioning a moving body that moves on a linear track at a desired position. In the present embodiment, the carriage 8 described above corresponds to the moving body.
As shown in FIG. 2, the positioning control device 20 includes a servo motor (elevating motor) 13 for driving the carriage 8 that is a moving body, an incremental encoder 21 that detects the rotation amount of the servo motor 13, and positioning. A servo driver 22 that drives and controls the servo motor 13 in response to a control signal and a detection signal from the encoder 21, a laser rangefinder 23 that measures the position of the carriage 8 on a straight track (here, the lift track of the carriage 8), a carriage And a control device 16 that stores positioning data of 8 and outputs a positioning control signal to the servo driver 22.

The servo motor 13 is preferably a synchronous AC servo motor 13 or the like. The encoder 21 is connected to the rotation shaft of the servo motor 13 and outputs a pulse signal corresponding to the rotation amount.
The servo driver 22 receives a positioning control signal (movement amount) from the control device 16 and also receives a feedback pulse signal from the encoder 21, executes necessary calculations, and drives and controls the servo motor 13 by feedback control. . Thus, the servo motor 13, the encoder 21 and the servo driver 22 constitute a servo mechanism for positioning the carriage 8 at a desired position.

  The laser rangefinder 23 in the present embodiment is installed at an appropriate position of the stacker crane 1, and the position of the carriage 8 can be accurately measured by measuring the distance from the installation position to the carriage 8. . In the present embodiment, the laser rangefinder 23 is installed on the carriage 3 of the stacker crane 1 so that the laser irradiation direction is directly above, and receives light reflected from the reflection plate 24 attached to the lower surface of the carriage 8 by the light receiving unit. It is like that. The measurement data of the laser distance meter 23 is transmitted to the control device 16. The laser distance meter 23 may be installed on the upper frame 7 side.

The control device 16 is a PLC, for example, and stores positioning data of the carriage 8. For teaching the positioning data to the control device 16, after the stacker crane 1 is installed in the automatic warehouse, the carriage 8 is sequentially moved to each stop position to be stored and stopped. At each position, the carriage 8 is moved by the laser distance meter 23. Can be carried out by measuring the position of and storing the measured value in the control device 16. Conventionally, positioning data has been stored in the servo driver 22, but in the present invention, since it is stored in the control device 16 having a large storage capacity, the limitation of the storage capacity can be eliminated, and the positioning data is much larger. Can be remembered.
The control device 16 transmits a positioning control signal (movement amount) to the servo driver 22 when positioning the carriage 8 at a desired position. Note that the electronic gear function of the servo driver 22 can be used to match the values on the laser distance meter 23 and the servo driver 22 side.

Next, the operation, action, and effect of the positioning control device 20 according to the present embodiment will be described.
As described above, since the encoder 21 is an incremental type, it is necessary to preset the encoder 21 prior to the positioning control operation of the carriage 8 after the power is turned on. This preset is performed as follows.
After the power is turned on, the control device 16 measures the position of the carriage 8 with the laser distance meter 23 prior to the positioning control operation of the carriage 8 and presets the encoder 21 using this measurement data.
As described above, according to the present invention, since the origin return operation that has been conventionally performed is unnecessary, the encoder 21 can be preset in a short time after the power is turned on. Moreover, there is no need to install an origin sensor.

Next, the carriage 8 is moved up and down and positioned at a desired position. Note that the positioning of the stacker crane 1 in the traveling direction of the carriage 3 is performed by driving control of the traveling motor 5 by the control device 16 at the same time as raising / lowering the carriage 8 or before and after the positioning.
The control device 16 receives a loading / unloading command from a host computer (not shown) and transmits a positioning control signal (movement amount) of the carriage 8 to the servo driver 22. The servo driver 22 receives a signal from the control device 16 and also receives a feedback pulse signal from the encoder 21, executes necessary calculations, and drives and controls the servo motor 13 by feedback control.

Subsequently, the control device 16 acquires the stop position of the carriage 8 moved by the drive of the servo motor 13 by the laser distance meter 23, and when the stop position based on the measurement data of the laser distance meter 23 does not coincide with the target stop position. Based on the measurement data from the laser distance meter 23, a control signal is output to the servo driver 22 so that the carriage 8 moves to the target stop position.
In this manner, in addition to monitoring the stop position by feedback control of the servo mechanism, the laser distance meter 23 also monitors the stop position, so that double stop position monitoring is possible. If the stop position based on the measurement data of the laser distance meter 23 does not coincide with the target stop position, the position of the carriage 8 is corrected based on the measurement data of the laser distance meter 23, so that highly accurate positioning can be performed. it can.

Further, when the stop position of the carriage 8 does not coincide with the target stop position as described above, the control device 16 corrects the positioning data based on the deviation amount.
Thus, since the positioning data is stored in the control device 16, the correction can be easily performed. Further, since the positioning data is corrected as described above, the carriage 8 can be positioned at the target stop position quickly and accurately without performing position correction again at the next positioning to the same position.

  Even when the servo driver 22 is in an uncontrollable state for some reason, the carriage 8 can be safely stopped by monitoring the carriage 8 with the laser distance meter 23.

  As is apparent from the above description, according to the present invention, the time required for encoder presetting can be greatly reduced, the origin sensor need not be disposed, and the storage capacity of positioning data can be limited. The positioning data can be monitored on the control device side, and the positioning data can be easily corrected.

  In the above-described embodiment, the present invention is applied to the positioning control of the carriage of the stacker crane. However, the moving body to be positioned can be the above-described carriage, and can be applied to the positioning control of the carriage. In addition, the present invention can be widely applied to positioning control of a moving body that moves on a linear track, such as a linear motion carriage of an overhead crane.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention disclosed above are merely examples, and the scope of the present invention is not limited to these embodiments. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

It is a figure which shows the stacker crane to which the positioning control apparatus of this invention is applied. It is a block diagram of the positioning control apparatus concerning embodiment of this invention. It is a figure which shows the conventional stacker crane.

Explanation of symbols

1 Stacker Crane 2 Traveling Roller 3 Cart 4 Traveling Rail 5 Traveling Motor 6 Mast 7 Upper Frame 8 Carriage 9 Sheave 11 Winch 12 Wire 13 Servo Motor (Elevating Motor)
14 Fork 15 Guide rail 16 Controller 20 Positioning controller 21 Encoder 22 Servo driver 23 Laser distance meter 24 Reflector

Claims (3)

In a positioning control device that positions a moving body that moves on a linear track at a desired position,
A servo motor that drives the moving body;
An incremental encoder for detecting the rotation amount of the servo motor;
A servo driver that drives and controls the servo motor in response to a positioning control signal and a detection signal from the encoder;
A laser rangefinder that measures the position of the moving body in the linear trajectory;
A controller that stores positioning data of the moving body and outputs a positioning control signal to the servo driver;
The control device presets an encoder by using measurement data from the laser distance meter prior to a positioning control operation of the moving body after power is turned on.   The control device acquires the stop position of the moving body moved by the drive of the servo motor with a laser distance meter, and when the stop position based on the measurement data of the laser distance meter does not match the target stop position, The positioning control device according to claim 1, wherein a control signal is output to the servo driver so that the moving body moves to a target stop position based on the measured data.   The positioning control device according to claim 2, wherein when the stop position of the moving body does not coincide with the target stop position, the control device corrects the positioning data based on the deviation amount.

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