WO2022209472A1

WO2022209472A1 - Linear motor transport system and method for operating same

Info

Publication number: WO2022209472A1
Application number: PCT/JP2022/007675
Authority: WO
Inventors: 直樹岸; 和彦小島
Original assignee: 住友重機械工業株式会社
Priority date: 2021-03-30
Filing date: 2022-02-24
Publication date: 2022-10-06
Also published as: JPWO2022209472A1; CN117044098A

Abstract

This linear motor transport system 100 comprises a carrier 10 to which a linear scale 14 and a reference mark 16 are fixed, a linear motor 12 that moves the carrier 10 along a route D, a plurality of sensors 18 arranged along the route D, and a control device 20. When the linear motor 12 is controlled such that the carrier 10 is moved as an initial process, the control device 20 identifies the position of the carrier 10 not on the basis of a reference-mark 14-related output produced by a sensor 18 that has not detected the linear scale 16 among the plurality of sensors 18, but rather on the basis of a reference-mark 14-related output produced by a sensor 18 that has detected the linear scale 16.

Description

Linear motor transfer system and its operation method

The present invention relates to a linear motor transport system and its operating method.

Conventionally, as a transport system for transporting an article, a linear motor transport system is known in which a carrier is driven using a linear motor as a drive source, and the carrier transports the article. A linear motor transport system includes a carrier that holds an article to be transported, a linear motor mover attached to the carrier, a linear motor stator including a plurality of electromagnets (coil units) arranged along a path, and a plurality of electromagnets. a control device for controlling current supply to the carrier to move the carrier along the path, and the mover travels along the path to convey the article held by the carrier.

In contrast to conventional conveyors, which convey items in the same direction at a constant speed, the linear motor transport system can individually control the movement of multiple carriers that hold the items. It also allows flexible control, such as stopping the carriers exactly where they are needed, changing their speed, or moving only one carrier in the opposite direction. In addition, since the linear motor transport system is driven by a linear motor, it is cleaner than the transport systems employing other drive systems because it does not generate dust and the like.

Therefore, the linear motor transport system has a wide variety of applications, such as transport between processes and processing lines that perform precision machining on the transport route.

In a linear motor transport system, it is necessary to keep track of the position of the mover relative to the stator in order to control the position of the mover. Conventionally, there has been proposed a linear motor transport system that detects the position of the mover by reading a linear scale provided on the stator side with a sensor provided on the mover side (for example, Patent Document 1).

JP 2014-219296 A

In the conventional linear motor transfer system as described in Patent Document 1, since a sensor is provided on the mover side, wiring for outputting the detection result of the sensor must be drawn from the mover side, and the movable range of the mover is limited. constraints.

The present invention has been made in this situation, and one exemplary purpose of certain aspects thereof is to provide a linear motor transport system with increased commercial value.

In order to solve the above problems, a linear motor transport system according to one aspect of the present invention includes a carrier to which a linear scale and reference marks are fixed, a linear motor that moves the carrier along a predetermined path, and An array of sensors and a controller. When the carrier is moved as an initial process by controlling the linear motor, the control unit detects the linear scale regardless of the reference mark output from the sensor that does not detect the linear scale among the plurality of sensors. The position of the carrier is determined based on the output of the sensor with respect to the reference mark.

Another aspect of the present invention is a method of operating a linear motor transport system. This method is a method of operating a linear motor transport system that includes a carrier to which a linear scale and reference marks are fixed, and a linear motor that moves the carrier along a predetermined path, and moves the carrier as an initial process. and specifying the position of the carrier based on the output regarding the reference mark by the sensor detecting the linear scale, not based on the output regarding the reference mark by the sensor not detecting the linear scale out of the plurality of sensors. and including.

It should be noted that any combination of the above constituent elements, and mutual replacement of the constituent elements and expressions of the present invention between methods, devices, systems, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to provide a linear motor transport system with increased commercial value.

1 is a plan view of a linear motor transport system according to an embodiment; FIG. FIG. 2 is a side view showing the carrier in FIG. 1 and its surroundings; FIG. 2 is a timing chart showing sensor output when the carrier in FIG. 1 is moved as an initial process; FIG.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. The embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention. The same or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and duplication of description will be omitted as appropriate.

FIG. 1 is a plan view showing a schematic configuration of a linear motor transport system 100 according to an embodiment. FIG. 2 is a side view showing the carrier 10 of the linear motor transport system 100 and its surroundings.

A linear motor transport system 100 includes a carrier 10 for holding an article to be transported, a linear motor 12 for driving the carrier 10, a reference mark 14 and a linear scale 16 fixed to the carrier 10, and a movable carrier 10. A plurality of sensors 18 arranged along the path P and a control device 20 that controls the linear motor transport system 100 are provided. Each of the plurality of sensors is connected to the control device 20 by wire. Although the number of carriers 10 is assumed to be one for ease of understanding, this is not a limitation, and a plurality of carriers 10 are normally provided.

The linear motor 12 has a stator 22 and a mover 24 attached to the carrier 10 .

The stator 22 is formed in a rectangular shape elongated in the D direction in plan view in this embodiment. The stator 22 includes a plurality of electromagnets (coil units) 26 arranged in the D direction. Only some of the electromagnets 26 are shown in FIG. 1 as an example. A current can be individually supplied from the power supply 34 to the plurality of electromagnets 26 . The array of multiple electromagnets 26 defines a path P. FIG. Although not particularly limited, the path P is linear in the present embodiment.

The mover 24 is attached to the lower surface of the carrier 10 so as to vertically face the electromagnet 26 . The mover 24 is configured including a magnet. The mover 24 moves along the path P due to the interaction of the magnetic field generated by the electromagnet 26 and the magnetic field of the magnet of the mover 24 .

The stator 22 may be provided with a linear guide that guides the movement of the mover 24 or the carrier 10. Alternatively, the mover 24 may be magnetically levitated above the stator 22 without providing a linear guide.

The reference mark 14 is provided on the lower surface of the carrier 10 in this example. Note that the reference mark 14 may be provided on the linear scale 16 . The reference mark 14 is not particularly limited, but may be a magnet if the sensor 18 is magnetic, or a glass or steel tape with a mark if it is optical.

The position of the reference mark 14 in the D direction on the carrier 10 (hereinafter simply referred to as the position of the reference mark 14) is preferably the reference position of the carrier 10 in the D direction (hereinafter simply referred to as the reference position of the carrier 10). match. The reference position is a reference position of the carrier 10 in the D direction, typically the center position of the carrier 10 in the D direction. If the position of the reference mark 14 matches the reference position of the carrier 10 , the position of the reference mark 14 will be the position of the carrier 10 .

The reference mark 14 may be provided at any position on the carrier 10, but the relative position of the reference mark 14 with respect to the reference position must be known. When the position of the reference mark 14 does not match the reference position of the carrier 10, the position of the carrier 10 is specified by considering the distance between the reference position and the reference mark 14 in the D direction in the absolute position of the reference mark 14. .

In the following, for simplicity of explanation, the position of the reference mark 14 is assumed to match the reference position of the carrier.

The linear scale 16 is fixed to the lower surface of the carrier 10 in the same way as the reference mark 14 in this example. The linear scale 16 is not particularly limited, but if the sensor 18 is magnetic, it is a magnet scale, and if it is optical, it is, for example, a graduated glass scale or steel tape. The linear scale 16 is provided on the carrier 10 so that the center of the linear scale 16 in the D direction coincides with the reference position of the carrier 10, although this is not a limitation.

The linear scale 16 has an effective area 16a and two ineffective areas 16b adjacent to both ends of the effective area 16a in the D direction. The effective area 16a is an area where the sensor 18 can read the scale, and the ineffective area 16b is an area where the sensor 18 cannot read the scale.

The sensor 18 includes a mark detection section 28 configured to detect the reference mark 14 and a scale detection section 29 configured to detect the linear scale 16 . In the present embodiment, the sensor 18 is arranged such that the mark detection section 28 is positioned on the movement path of the reference mark 14 and the scale detection section 29 is positioned on the movement path of the linear scale 16 in plan view. .

When the mark detection unit 28 detects the reference mark 14, that is, when the reference mark 14 passes right above the mark detection unit 28, it outputs a pulse signal having a predetermined intensity or more to the control device 20. The pulse width of the pulse signal is preferably about the same as the resolution of the mark detection section 28, but may be longer. Although the details will be described later, the control device 20 determines whether or not the reference mark 14 is positioned right above the mark detection section 28 based on the signal output from the mark detection section 28 .

The scale detector 29 reads the scale provided on the linear scale 16 that moves above the scale detector 29, and every time the linear scale 16 and thus the carrier 10 moves R [μm] (R is the resolution of the scale detector 29). , a pulse signal of one pulse is output to the control device 20 . That is, the scale detector 29 outputs the number of pulse signals corresponding to the moving distance of the linear scale 16 and thus the carrier 10 . The controller 20 identifies (detects) the position of the carrier 10 in the D direction or the amount of change in the position by counting the pulse signals output by the scale detector 29 . In addition, below, the case where a position is pinpointed is demonstrated.

Although not particularly limited, the plurality of sensors 18 are arranged at regular intervals in this example. Specifically, they are arranged at an interval S. In particular, the plurality of sensors 18 are arranged such that the interval S between the sensors 18 and the length Le of the effective area 16a of the linear scale 16 (hereinafter referred to as "effective area length") satisfy the relationship "interval S<effective area length Le". placed in In this case, regardless of where the carrier 10 is positioned on the path P, the effective area 16a of the linear scale 16 is positioned in the detection area of one of the sensors 18 (that is, directly above the sensor 18), so the position of the carrier 10 can be identified. It is assumed that the position of each of the multiple sensors 18 is known.

The control device 20 includes a position specifying section 30 and a linear motor control section 32 that controls the linear motor 12 to move the carrier 10 .

The linear motor control unit 32 controls current supply from the power supply 34 to each electromagnet 26 while feeding back the positional information of the carrier 10 specified by the position specifying unit 30 as will be described later, thereby moving the carrier 10 to a desired position. move to

The position specifying unit 30 specifies the position of the carrier 10 based on the output of the sensor 18.

The linear motor transport system is stopped and started periodically or irregularly. For example, some factories shut down at the end of working hours and start up at the beginning of working hours for safety reasons. Also, for example, when a linear motor transport system is used for each of a plurality of processing lines, the number of processing lines to be operated increases or decreases as the number of orders for products increases or decreases. I have something to do.

When the linear motor transport system stops, specifically when the control device is turned off, the carrier position information held by the control device disappears. Although it is conceivable that the controller retains the position information, there is no guarantee that the carrier will not move while the linear motor transport system is stopped. Therefore, it is necessary to specify the position when starting the linear motor transport system.

Therefore, in the linear motor transport system 100, as an initial process immediately after starting, the linear motor control unit 32 moves the carrier 10 and causes one of the sensors 18 to detect the reference mark 14 to specify the position of the carrier 10. do.

The position specifying unit 30 detects the threshold intensity from the mark detection unit 28 of one of the sensors 18_1 to 18_N (N is an integer of 2 or more, and N is 3 or more in the examples of FIGS. 1 to 3). When the above (hereinafter also referred to as high-level) signals are output, specifically, when a high-level signal is output from the first detection unit 28 of the sensor 18_i, the reference mark is placed directly above the sensor 18_i. 14 and thus the carrier 10 is located. The position specifying unit 30 determines the sensor 18 — i that has detected the reference mark 14 as a reference sensor (hereinafter referred to as “reference sensor”) for specifying the absolute position of the carrier 10 .

The position specifying unit 30 counts the pulse signals output from the scale detection unit 29 of the reference sensor as the carrier 10 moves, with the reference mark 14 positioned directly above the reference sensor as "0". .

The position specifying unit 30 specifies the distance of the carrier 10 from the reference sensor, that is, the relative position of the carrier 10 with respect to the reference sensor, based on the count value of the pulse signal output from the scale detection unit 29 of the reference sensor. The position specifying unit 30 specifies the position of the carrier 10 by adding the specified relative position to the position of the reference sensor.

When the carrier 10 moves to some extent, the effective area 16a of the linear scale 16 deviates from the detection range (that is, directly above) of the scale detection section 29 of the reference sensor. Then, the position of the carrier 10 cannot be specified based on the output of the reference sensor. Therefore, before the effective area 16a of the linear scale 16 deviates from the detection range of the reference sensor, the sensor 18 adjacent to the reference sensor and having the effective area 16a of the linear scale 16 in its detection range (that is, directly above) is detected. 18 should be taken as the new reference sensor. That is, it is necessary to switch the reference sensor.

Specifically, for example, when the sensor 18 — i is the reference sensor, the carrier 10 moves to the right side of the paper surface in the D direction, and the relative position (pulse signal count value) of the carrier 10 with respect to the sensor 18 — i is set to a predetermined value. , the adjacent sensor 18_i+1 is set as a new reference sensor. Therefore, until then, the position specifying unit 30 specified the absolute position of the carrier 10 by specifying the relative position of the carrier 10 with respect to the sensor 18_i. The absolute position of the carrier 10 is specified by specifying . That is, the position of the carrier 10 is specified by adding the position of the carrier 10 relative to the sensor 18_i+1 to the position of the sensor 18_i+1.

As described above, the position specifying unit 30 continues to repeatedly specify the position of the carrier 10 while switching the reference sensor as the carrier 10 moves.

By the way, it is generally assumed that the sensor 18 is used with the scale detection unit 29 constantly detecting the linear scale 16 . As a result of diligent studies by the present inventors, when the scale detection unit 29 does not detect the linear scale 16, the output of the mark detection unit 28 becomes indefinite. I recognized that it outputs a high level signal. Therefore, when the reference sensor is determined based on the detection result of the reference mark 14 in the initial processing, if the output from the mark detection unit 28 is used without selection, the reference sensor is determined erroneously, and the position of the carrier 10 is determined. may be incorrectly identified. This will be described in detail with reference to FIG.

FIG. 3 is a time chart showing outputs from the sensor 18 when the carrier 10 is moved as initial processing.

At time _t0 , power supply to each sensor 18 is started. _At time t1, the supply of current to electromagnet 26 is started. Due to the current supply to the electromagnet 26, the carrier 10 is moving to the right in this example. _At time t2, (the right end of) the effective area 16a of the linear scale 16 reaches just above the scale detection portion 29 of the sensor 18_1. At time t3 _, the reference mark 14 reaches just above the mark detection portion 28 of the sensor 18_1. At time t4, ₍ the right end of) the effective area 16a of the linear scale 16 reaches just above the scale detection portion 29 of the sensor 18_2. In other words, in the effective area 16a of the linear scale 16, the linear scale 16 is positioned directly above the scale detection portions 29 of both the sensors 18_1 and 18_2. _At time t5, the linear scale 16 reaches the right side of the sensor 18_1. In other words, the linear scale 16 is out of position directly above the sensor 18_1. At time t6, the reference mark ₁₄ reaches just above the mark detection portion 28 of the sensor 18_2.

From time t ₀ to time t ₄ , the effective area 16 a of the linear scale 16 is not directly above the scale detection section 29 of the sensor 18_2, and therefore the scale detection section 28 does not detect the linear scale 16 . Therefore, the output of the mark detection section 28 of the sensor 18_2 is indefinite from time t ₀ to time t ₄ , and even though the reference mark 14 is not located directly above the mark detection section 28 of the sensor 18_2, this example outputs a high-level signal and a low-level signal. If the output of the mark detection section 28 of the sensor 18_2 from time t ₀ to time t ₄ is used to determine the reference sensor, the position of the carrier 10 may be erroneously identified.

Also, the effective area 16a of the linear scale 16 is not directly above the scale detection section 29 of the sensor 18_3 at each time in FIG. Therefore, the output of the mark detection section 28 of the sensor 18_3 at each time in FIG. A level signal is output and a low level signal is output. If the output of the sensor 18_3 at each time in FIG. 3 is used to determine the reference sensor, the position of the carrier 10 may be specified incorrectly.

Also, until _time t2, the effective area 16a of the linear scale 16 is not directly above the scale detection section 29 of the sensor 18_1, so the scale detection section 29 does not detect the linear scale 16. FIG. Therefore, the output of the mark detection unit 28 of the sensor _{18_1} is indefinite until time t2, and even though the reference mark 14 is not positioned right above the sensor _{18_2} , the time t2 is reached in this example. It continues to output a high level signal until _At time t2, the effective area 16a of the linear scale 16 is positioned right above the scale detector 29 of the sensor 18_1, so the scale detector 29 correctly outputs a low level signal. That is, at time t2, the _output of the mark detection section 28 of the sensor 18_1 changes even though the reference mark 14 is not positioned right above the mark detection section 28 of the sensor 18_1. If the output of sensor _{18_1} at time t2 is used to determine the reference sensor, the position of carrier 10 may be erroneously determined.

At time t3 _, the effective area 16a of the linear scale 16 is directly above the scale detection section 28 of the sensor 18_1, so the scale detection section 28 detects the linear scale 16. FIG. Therefore, the output of the mark detection section 28 of the sensor _{18_1} at time t3 is the output from the actual detection of the reference mark 14 . Here, as described above, in the present embodiment, the plurality (all) of the sensors 18 are equidistantly arranged at an interval S (interval S<effective area length Le), but other configurations are also conceivable. . That is, the plurality of sensors 18 may be arranged such that the distance between adjacent sensors 18 is equal to or greater than the effective area length Le. In this case, when adopting the output when the effective area 16a of the linear scale 16 is directly above only one sensor 18 as at time t3 _, the effective area 16a of the linear scale 16 is from directly above the scale detector 29. There is a risk of adopting the output of the mark detection section 28 due to deviation (that is, the output becomes unstable).

Therefore, the position specifying unit 30 of the present embodiment is not based on the output from the mark detection unit 28 of the sensor 18 for which the scale detection unit 29 does not detect the linear scale 16 among the plurality of sensors 18, and the scale detection unit 29 specifies the position of the carrier 10 based on the output from the mark detection section 28 of the sensor 18 detecting the linear scale 16 . After the scale detection units 29 of two adjacent sensors 18 out of the plurality of sensors have detected the linear scale 16 at the same time, the position specifying unit 30 moves forward in the moving direction of the carrier 10 out of the two sensors 18 . The position of the carrier 10 is specified based on the output from the mark detection section 28 of the sensor 18 located at . This avoids erroneous detection of the reference mark 14 and thus erroneous positioning of the carrier 10 .

For example, in the illustrated example, the position specifying unit 30 detects two adjacent sensors 18_1 and 18_2 of the plurality of sensors 18 after the scale detection units 29 of the two sensors 18_1 and 18_2 detect the linear scales 16 at the same time. The position of the carrier 10 is specified based on the output from the mark detection unit 28 of the sensor 18_2 positioned on the front side (right side) in the movement direction of the carrier 10 (that is, the output at time t6).

Two adjacent sensors 18 detecting the linear scale 16 at the same time match the timing at which the number of counts based on the pulse signals output by the scale detectors 29 changes according to the moving distance of the linear scale 16 a predetermined number of times. It is also possible to have two sensors connected to each other.

The predetermined number of times is preferably a plurality of times. In this case, it can be said that the two adjacent sensors 18 reliably detect the linear scale 16 at the same time. The predetermined number of times may be six times, for example. In this case, for example, the number of counts based on the detection of the linear scale 16 by the sensor 18_1 is 12→13, 13→14, 14→15, 15→16, 16→17. , 17→18, and the number of counts based on the detection of the linear scale 16 by the sensor 18_2 switches 0→1, 1→2, 2→3, 3→4, 4→5, 5→6. Since the six timings match, it is determined that the sensors 18_1 and 18_2 are detecting the linear scale 16 at the same time.

Next, the effects of the embodiment will be explained. According to this embodiment, the position of the carrier 10 can be detected by the sensor 18 provided on the stator 22 side. It becomes unnecessary to mount a battery on the carrier 10 or draw wiring from the carrier 10. - 特許庁

Further, according to the present embodiment, the scale detector 29 of the plurality of sensors 18 does not detect the linear scale 16, and the scale detector 29 detects the linear scale not based on the output of the mark detector 28 of the sensor 18. The position of the carrier 10 is specified based on the output of the mark detection section 28 of the sensor 18 that detects the scale 16 . As a result, erroneous detection of the reference mark 14 can be avoided, and the position of the reference mark 14 and thus the carrier 10 can be specified.

Further, according to the present embodiment, after the scale detection units 29 of two adjacent sensors 18 among the plurality of sensors simultaneously detect the linear scale 16, the carrier 10 of the two sensors 18 moves. The position of the carrier 10 is specified based on the output from the mark detection section 28 of the sensor 18 located on the forward side. As a result, erroneous detection of the reference mark 14 can be more reliably avoided, and the position of the reference mark 14 and thus the carrier 10 can be specified.

The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that this embodiment is merely an example, and that various modifications can be made to combinations of each component and each treatment process, and that such modifications are within the scope of the present invention. be. Modifications will be described below.

Any combination of the above-described embodiment and modifications is also useful as an embodiment of the present invention. A new embodiment resulting from the combination has the effects of the combined embodiment and modifications.

10 carrier, 12 linear motor, 14 reference mark, 16 linear scale, 18 sensor, 20 controller, 100 linear motor transfer system.

Claims

a carrier with fixed linear scale and reference mark;
a linear motor that moves the carrier along a predetermined path;
a plurality of sensors arranged along the path;
a controller;
with
When the carrier is moved by controlling the linear motor to move the carrier as an initial process, the control device is not based on an output regarding the reference mark from a sensor that does not detect the linear scale among the plurality of sensors. , a linear motor transport system for determining the position of said carrier based on the output of said reference mark by a sensor sensing said linear scale;
The output related to the reference mark used to specify the position of the carrier is the movement of the carrier among the two sensors after two adjacent sensors among the plurality of sensors simultaneously detect the linear scale. 2. A linear motor transport system according to claim 1, wherein said reference mark is output by a sensor located on the front side of the direction.
The two adjacent sensors detecting the linear scale at the same time are two sensors whose timings of changing the count number based on the pulse signal output according to the moving distance of the linear scale coincide a predetermined number of times. 3. The linear motor transport system according to 2.
The linear motor transport system according to claim 3, wherein the predetermined number of times is a plurality of times.
A method of operating a linear motor transport system comprising a carrier to which a linear scale and a reference mark are fixed, a linear motor for moving the carrier along a predetermined path, and a plurality of sensors arranged along the path There is
moving the carrier as an initial process;
The position of the carrier is determined not based on the output regarding the reference mark by a sensor not detecting the linear scale among the plurality of sensors, but based on the output regarding the reference mark by the sensor detecting the linear scale. to identify;
Operation method of a linear motor transport system including.