KR102552246B1 - Conveying system using linear motor and Operating method thereof - Google Patents

Abstract

According to the present invention, a linear motor conveying system with increased product value is provided.
The linear motor transport system 100 controls a carrier 10 driven by a linear motor 12, a plurality of sensors 18 disposed along a predetermined path P, and the linear motor 12 , and a control device 20 for moving the carrier 10 along the path P. The control device 20 switches among the plurality of sensors 18 a reference sensor whose output is used to specify the position of the carrier in the plurality of sensors 18 according to the movement of the carrier 10 .

Description

Linear motor conveying system and operating method thereof {Conveying system using linear motor and operating method thereof}

This application claims priority based on Japanese Patent Application No. 2020-144625 filed on August 28, 2020. The entire content of that application is incorporated herein by reference.

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

BACKGROUND OF THE INVENTION [0002] Conventionally, as a conveying system for conveying articles, a linear motor conveying system is known in which a linear motor is used as a drive source to drive a carrier to convey articles by means of the carrier. The linear motor conveying system includes a carrier holding articles to be conveyed, a linear motor mover mounted on the carrier, a stator of the linear motor including a plurality of electromagnets (coil units) arranged along a path, and a plurality of electromagnets. A control device for controlling the supply of current to the carrier to move the carrier along the path is provided, and the mover travels along the path to transport the article held in the carrier.

Conventional conveyors flow goods, which are conveyed goods, in the same direction at a constant speed, whereas the linear motor conveying system can individually control the movement of a plurality of carriers holding the goods. In addition, flexible control such as stopping the carrier precisely at the required location, changing the speed, or moving only one carrier in the opposite direction can be performed. In addition, since the linear motor conveyance system is driven by a linear motor, compared to conveyance systems adopting other driving methods, dust and the like are not generated, so it is clean.

Therefore, the linear motor transport system is used in a wide variety of fields, for example, transport between processes and processing lines that perform precision processing on a transport route.

In the linear motor conveying 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, a linear motor transport system has been proposed that detects the position of a mover by reading a linear scale provided on the stator side with a sensor provided on the mover side (for example, Patent Document 1).

Patent Document 1: Japanese Unexamined Patent Publication No. 2014-219296

In the conventional linear motor transport system described in Patent Literature 1, since a sensor is provided on the mover side, it is necessary to provide a battery for supplying power to the sensor on the mover side, and its maintenance is required. In addition, it is necessary to lead a wire for outputting a detection result by the sensor from the mover side, which limits the movable range of the mover.

The present invention has been made in such a situation, and one of the exemplary objects of one aspect is to provide a linear motor conveying system with increased product value.

In order to solve the above problems, the linear motor conveying system of one aspect of the present invention controls a carrier driven by a linear motor, a plurality of sensors disposed along a predetermined path, and a linear motor to route the carrier Equipped with a control device that moves along. The controller switches among the plurality of sensors a reference sensor whose output is used to specify the position of the carrier in the plurality of sensors according to the movement of the carrier.

Another aspect of the present invention is a method for operating a linear motor transport system. This method is a method for operating a linear motor transport system comprising a carrier driven by a linear motor, a plurality of sensors disposed along a predetermined path, and a control device for controlling the linear motor to move the carrier along the path. A reference sensor specifying step for specifying a reference sensor using the detection result from among a plurality of sensors to specify the position of the carrier, and a position specifying step for repeatedly specifying the position of the carrier based on an output from the reference sensor. . The position specifying step includes a step of switching reference sensors within a plurality of sensors according to the movement of the carrier.

However, any combination of the above constituent elements and substitution of the constituent elements or expressions of the present invention with each other among methods, devices, systems, etc. are also effective as embodiments of the present invention.

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

1 is a plan view of a linear motor transport system according to an embodiment.
Figure 2 is a side view showing the carrier of Figure 1 and its surroundings.
3 is a side view showing the carrier of FIG. 1 and its surroundings.
4 is a side view showing the carrier of FIG. 1 and its surroundings.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated, referring drawings based on preferred embodiment. Embodiments are examples that do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, members, and processes appearing in each drawing shall have the same reference numerals, and appropriately overlapping descriptions are omitted.

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

The linear motor conveying system 100 includes a carrier 10 for holding an article to be conveyed, a linear motor 12 for driving the carrier 10, a reference mark 14 fixed to the carrier 10, and a linear It has a scale 16, a plurality of sensors 18 arranged along the transport path P of the carrier 10, and a control device 20 that collectively controls the linear motor transport system 100. Each of the plurality of sensors is connected to the control device 20 by wire. However, for ease of understanding, although the number of carriers 10 is set to one, it is not limited thereto, and a plurality of carriers 10 are usually provided.

The linear motor (12) includes a stator (22) and a mover (24) mounted on a carrier (10).

In this embodiment, the stator 22 is formed in a rectangular shape elongated in the D direction in plan view. The stator 22 includes a plurality of electromagnets (coil units) 26 arranged along the extension direction. In Fig. 1, only some electromagnets 26 are shown as examples. Electric current can be individually supplied from the power source 34 to the plurality of electromagnets 26 . An arrangement of a plurality of electromagnets 26 defines a path P. Although not particularly limited, in the present embodiment, the path P is linear.

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

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

The reference mark 14 is a mark indicating a reference position. The reference mark 14 is not particularly limited, but is a magnet if the sensor 18 is of a magnetic type, and is glass or steel tape with a mark, for example, if the sensor 18 is of an optical type.

The reference mark 14 is provided on the lower surface of the carrier 10 here. However, the reference mark 14 may be provided on the linear scale 16. The reference mark 14 is preferably provided such that its position in the D direction coincides with the "position reference portion" of the carrier 10. The position reference portion is a portion serving as a reference for the position of the carrier 10 in the D direction, and is typically a center portion of the carrier 10 in the D direction. When the position of the reference mark 14 in the D direction coincides with the position of the position reference unit in the D direction, the absolute position of the reference mark 14 becomes the absolute position of the carrier 10.

The reference mark 14 may be provided at an arbitrary position on the carrier 10, but it is necessary that the position relative to the position reference unit is already known (determined in advance). If the position of the reference mark 14 in the D direction does not coincide with the position of the positioning reference part in the D direction, the absolute position of the reference mark 14 corresponds to the positioning reference part and the reference mark 14 in the D direction. By considering the distance in , the absolute position of the carrier 10 is specified.

Hereinafter, for simplicity of explanation, it is assumed that the position of the reference mark 14 in the D direction coincides with the position of the position reference unit in the D direction.

The linear scale 16 is fixed to the lower surface of the carrier 10. The linear scale 16 is not particularly limited, but if the sensor 18 is of a magnetic type, it is a magnetic scale, and if it is an optical type, it is, for example, a scaled glass scale or steel tape. The linear scale 16 is mounted on the carrier 10 so that the center of the linear scale 16 in the D direction coincides with the position in the D direction of the position reference of the carrier 10, although it is not limited thereto. provided

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

The sensor 18 includes a first detector 28 configured to detect the reference mark 14 and a second detector 29 configured to detect the linear scale 16 . In this embodiment, in the sensor 18, in a planar view, the first detection unit 28 is located on the movement path of the reference mark 14, and the second detection unit 29 is located on the movement path of the linear scale 16. ) is arranged so that it is located.

When the first detection unit 28 detects the reference mark 14, that is, when the reference mark 14 passes right above the first detection unit 28, a pulse signal having a predetermined intensity or higher is sent to the controller 20. print out The pulse width of the pulse signal is preferably about the same as the resolution of the first detection unit 28, but may be longer than that. The control device 20 specifies whether or not the reference mark 14 is directly above the first detection unit 28 based on the signal output from the first detection unit 28, as described later in detail.

The second detection unit 29 reads the scale provided on the linear scale 16 moving upward of the second detection unit 29, and the linear scale 16 and thus the carrier 10 is R [μm] (R is Resolution of the second detector 29) A pulse signal of one pulse is output to the controller 20 whenever it moves. The controller 20 specifies (detects) the position of the carrier 10 in the D direction as will be described later by counting the pulse signal output from the second detection unit 29 .

The plurality of sensors 18 are arranged at equal intervals, here at intervals S. In addition, in the plurality of sensors 18, the length of the effective area 16a of the linear scale 16 (hereinafter referred to as "effective area length") Le and the distance S between the sensors 18 are "effective area length Le ≥ interval S". In this case, no matter where the carrier 10 is located on the path P, the effective area 16a of the linear scale 16 is the distance of any one sensor 18. Since it is located in the detection area (that is, right above the sensor 18), it is possible to specify the absolute position of the carrier 10 as will be described later. In any case, it is assumed that the absolute position of each of the plurality of sensors 18 is already known.

3 and 4 are side views showing the carrier 10 of the linear motor transport system 100 and its surroundings. In FIG. 3 , the reference mark 14 is located just above the sensor 18 . In Fig. 4, the center of the linear scale 16 and thus the carrier 10 is located at the midpoint of two adjacent sensors. The controller 20 will be described with reference to FIGS. 1 to 4 .

The control device 20 includes a position specifying unit 30 and a linear motor control unit 32 .

The position specifying unit 30 is a first detection unit 28 of any one sensor 18 among a plurality of sensors 18_1 to 18_N (N is an integer of 2 or more, and in the examples of FIGS. 2 to 4, N is 5 or more). ), when a signal with a threshold intensity or higher is output from the sensor 18_i, specifically, for example, when a signal with a threshold intensity or higher is output from the first detector 28 of the sensor 18_i, the reference mark 14 directly above the sensor 18_i. ) and further specifies that the carrier 10 is located. The position specifying unit 30 determines the sensor 18_i that detected the reference mark 14 as a reference sensor for specifying the absolute position of the carrier 10 (hereinafter referred to as a "reference sensor"). .

The position specifying unit 30 sets the time when the reference mark 14 is located right above the reference sensor as “0”, and the pulse output from the second detection unit 29 of the reference sensor according to the movement of the carrier 10 count the signals

The position specific unit 30 determines the distance from the reference sensor of the carrier 10, that is, the distance of the carrier 10 to the reference sensor, based on the count value of the pulse signal output from the second detection unit 29 of the reference sensor. Specifies the relative position. The position specifying unit 30 specifies the absolute position of the carrier 10 by adding a specific relative position to the absolute position of the reference sensor.

By the way, although it depends on the length of the linear scale 16, if the carrier 10 moves to some extent, the effective area of the linear scale 16 moves from the detection range of the second detection unit 29 of the reference sensor (i.e. right above). (16a) is off. In that case, 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, as the sensor 18 adjacent to the reference sensor, the linear scale 16 is effective in the detection range (ie immediately above). It is necessary to use the sensor 18 in the region 16a as a new reference sensor. That is, it is necessary to switch the reference sensor.

Specifically, the position specifying unit 30 moves the carrier 10 to the right side of the paper in the D direction in the case where the sensor 18_i is the reference sensor, for example, and the carrier 10 relative to the sensor 18_i When the relative position (count value of the pulse signal) of (10) reaches a predetermined value, the adjacent sensor 18_i+1 is used as a new reference sensor. Accordingly, the position specifying unit 30 has been specifying the absolute position of the carrier 10 by specifying the relative position of the carrier 10 with respect to the sensor 18_i until then, but after switching the reference sensor, the sensor 18_i+ 1) The absolute position of the carrier 10 is specified by specifying the position relative to the carrier 10. That is, the absolute position of the carrier 10 is specified by adding the relative position of the carrier 10 to the sensor 18_i+1 to the absolute position of the sensor 18_i+1.

However, when the reference sensor is switched, the relative position of the carrier 10 with respect to the sensor 18 of the switching line is based on the relative position of the carrier 10 with respect to the sensor 18_i of the switching source. to specify In other words, when switching the reference sensor, based on the count value of the pulse signal in the sensor 18_i of the switching source, the initial value of the count value of the pulse signal in the sensor 18_i + 1 of the switching line is specified do. Thereafter, the count value of the pulse signal output from the sensor 18_i+1 is integrated with the specified initial value.

In switching of the reference sensor, for example, as shown in FIG. 4, the center of the linear scale 16 (the center of the carrier 10 in this example) is adjacent to the reference sensor (sensor 18_i in this example) and the reference sensor. It may be performed at the timing when the intermediate point of the sensor (sensor 18_i+1 in this example) is reached.

In this case, the position specifying unit 30 determines the pulse signal output from the second detection unit 29 of the reference sensor when the carrier 10 moves to the right in the D direction in FIGS. When the count value (CNT) becomes the value obtained by the following equation (1), the reference sensor can be switched. However, here, in Figs. 1 to 4, the direction going to the right in the D direction is made a positive direction, and the direction going to the left is made a negative direction.

CNT=+1/2×(Ls-2X-2Y)×1/{R×1/1000}… (One)

step,

Ls: Length in the D direction of the linear scale 16 [mm]

X: Length in the D direction of the invalid area 16b existing at both ends of the linear scale 16 [mm]

Y: Distance from the invalid area 16b of the reference sensor at the switching source when switching the reference sensor [mm]

R: resolution of sensor 18 (1 count = R [μm])

am.

The positioning unit 30 calculates the initial value of the count value of the pulse signal output from the second detection unit 29 of the new reference sensor according to the movement of the carrier 10, the count value obtained by the following equation (2) (CNT) is set. That is, after switching of the reference sensor, the pulse signal output from the second detection unit 29 of the new reference sensor starts to be counted from the count value obtained by Equation (2).

CNT=-1/2×(Ls-2X-2Y)×1/{R×1/1000} . (2)

However, in Figs. 1 to 4, when the carrier 10 travels to the left in the D direction, that is, in the negative direction, the positives of Expressions (1) and (2) may be reversed.

As described above, the position specifying unit 30 repeatedly and continuously specifies the absolute position of the carrier 10 while switching the reference sensor according to the movement of the carrier 10 .

The linear motor controller 32 controls the linear motor 12 to move the carrier 10 . Specifically, the linear motor control unit 32 feeds back the position information of the carrier 10 specified by the position specification unit 30, while the electric current from the power source 34 to each electromagnet 26 of the stator 22 By controlling the supply of, the carrier 10 is moved to a desired position.

The above is the basic configuration of the linear motor transport system 100. Subsequently, the operation of the linear motor transport system 100 will be described with reference to FIGS. 2 to 4 . Time passes in the order of FIGS. 2, 3 and 4.

It is assumed that the state at the time of activation of the linear motor transport system 100 was the state in FIG. 2 . The control device 20 sends a constant current to the electromagnet 26 to move the carrier 10. In this way, it is assumed that the carrier 10 has moved to the right side in FIG. 2 .

In Fig. 3, the carrier 10 is reaching directly over the sensor 18_i. The sensor 18_i detects the reference mark 14 . Therefore, the sensor 18_i becomes the reference sensor. The control device 20 specifies the absolute position of the carrier 10 based on the count value of the pulse signal output from the reference sensor.

In Fig. 4, since the relative position of the carrier 10 with respect to the sensor 18_i, that is, the count value of the pulse signal in the sensor 18_i is the value obtained by equation (1), the reference sensor is the sensor 18_i ) to the sensor 18_i+1.

Subsequently, effects of the embodiments will be described. According to this embodiment, since the position of the carrier 10 can be detected by the sensor 18 provided on the side of the stator 22, a sensor is provided on the side of the carrier 10 to detect the position of the carrier 10. There is no need to provide, and therefore there is no need to mount the battery on the carrier 10 or pull out wires from the carrier 10.

Further, according to the present embodiment, even if the size of the carrier 10 is changed and thus the length of the linear scale 16 is changed or the resolution of the sensor 18 is changed, the equations (1) and (2) It is only necessary to change the value to be substituted for , and such a change can be easily responded to.

In the above, the present invention has been described based on the embodiments. This embodiment is an example, and it is understood by those skilled in the art that various modifications are possible for each component or combination of each processing process, and that such modifications are also within the scope of the present invention. A modified example will be described below.

In the embodiment, the case where a plurality of sensors 18 are arranged at equal intervals has been described, but if the interval between adjacent sensors 18 is equal to or less than the effective area length Le of the linear scale 16, adjacent sensors 18 The intervals may not be equal intervals. That is, the at least one sensor interval may be different from the other sensor intervals. In this case, the count value when switching the sensor 18 may be different, but the center of the linear scale 16 (in this example, the center of the carrier 10) reaches the midpoint of the adjacent sensor 18 In the case of switching the reference sensor at the timing, it is sufficient to switch at the timing at which the count value of the sensor 18 at the source of the switch becomes the count value obtained by equation (1).

Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiment generated by the combination combines the effects of each of the combined embodiments and modified examples.

10 carrier
12 linear motor
18 sensor
20 Controls
100 Linear Motor Transfer System

Claims (5)

A carrier driven by a linear motor;
A plurality of sensors arranged along a predetermined path;
A control device for controlling the linear motor to move the carrier along the path,
A carrier has a reference mark at the center of the carrier, and by outputting a pulse signal when the reference mark is detected, the controller selects, among the plurality of sensors, a reference sensor used for specifying the position of the carrier based on the output, switching within the plurality of sensors according to the movement of the carrier;
The carrier has a linear scale, and the linear scale has an effective area of a predetermined length, which is an area from which the sensor can read the scale, and an invalid area disposed at both ends of the effective area,
The plurality of sensors include a detection unit configured to detect the linear scale,
The linear motor transport system according to claim 1 , wherein the reference sensor is switched based on a count value of an output of a pulse signal from the detection unit of the reference sensor obtained from the length of the linear scale and the length of the invalid area. According to claim 1,
The control device specifies the position of the carrier based on the position of the reference sensor and the relative position of the carrier to the reference sensor specified based on the output from the reference sensor. system. According to claim 1 or 2,
The plurality of sensors include first and second sensors disposed adjacent to each other,
When the control device switches the reference sensor from the first sensor to the second sensor, based on the relative position of the carrier with respect to the first sensor specified based on the output from the first sensor, A linear motor transport system characterized in that the relative position of the carrier with respect to the second sensor is specified. According to claim 1 or 2,
A reference mark provided on the carrier,
Each of the plurality of sensors is configured to detect a reference mark,
When the relative position of the reference mark with respect to the reference part of the position of the carrier is already known,
The control device moves the carrier, detects the reference mark with any one of a plurality of sensors, and sets the sensor that detected the reference mark as the reference sensor, and the carrier relative to the reference sensor. Linear motor conveying system, characterized in that for specifying the relative position of. A carrier driven by a linear motor and having a reference mark in the center, a plurality of sensors disposed along a predetermined path, and a control device for controlling the linear motor to move the carrier along the path, The carrier has a linear scale, and the linear scale has an effective area of a predetermined length, which is an area in which the sensor can read the scale, and an invalid area disposed at both ends of the effective area, and the plurality of sensors have the As a method of operating a linear motor conveying system having a detection unit configured to detect a linear scale,
A reference sensor specifying step for specifying a reference sensor using an output from among the plurality of sensors to specify the position of the carrier;
And a position specifying step for repeatedly specifying the position of the carrier based on an output from the reference sensor,
The position specifying step includes a step of switching the reference sensor in the plurality of sensors according to the movement of the carrier based on an output of a pulse signal when the reference mark is detected,
In the position specifying step, the reference sensor is switched based on the count value of the output of the pulse signal from the detection unit of the reference sensor obtained from the length of the linear scale and the length of the invalid area Linear motor transport system, characterized in that How to operate.

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