阅读说明：本技术 线性马达输送系统及其运用方法 (Linear motor delivery system and method of using same ) 是由 岸直树 于 2021-03-29 设计创作，主要内容包括：根据本发明,提供一种提高商品价值的线性马达输送系统。本发明的线性马达输送系统(100)具备：托架(10),被线性马达(12)驱动；多个传感器(18),沿规定路径(P)配置；及控制装置(20),控制线性马达(12)以使托架(10)沿路径(P)移动。控制装置(20)伴随托架(10)的移动在多个传感器(18)中切换多个传感器(18)中的将输出用于托架的位置确定的基准传感器。(According to the present invention, a linear motor conveyance system is provided that improves the value of commercial products. A linear motor conveyance system (100) is provided with: a carriage (10) driven by a linear motor (12); a plurality of sensors (18) arranged along a predetermined path (P); and a control device (20) for controlling the linear motor (12) to move the carriage (10) along the path (P). The control device (20) switches, among the plurality of sensors (18), a reference sensor that uses the output of the plurality of sensors (18) for determining the position of the carriage (10) as the carriage moves.)

1. A linear motor conveying system is characterized by comprising:

a carriage driven by a linear motor;

a plurality of sensors arranged along a predetermined path; and

a control device that controls the linear motor to move the carriage along the path,

the control device switches, among the plurality of sensors, a reference sensor that uses an output for position determination of the carriage, among the plurality of sensors, in association with movement of the carriage.

2. The linear motor delivery system of claim 1,

the control device determines the position of the carriage based on the position of the reference sensor and the relative position of the carriage with respect to the reference sensor determined based on the output from the reference sensor.

3. Linear motor delivery system according to claim 1 or 2,

the plurality of sensors includes a 1 st sensor and a 2 nd sensor arranged adjacent to each other,

the control device determines the relative position of the carriage with respect to the 2 nd sensor based on the relative position of the carriage with respect to the 1 st sensor determined based on the output of the 1 st sensor when the reference sensor is switched from the 1 st sensor to the 2 nd sensor.

4. The linear motor delivery system of any one of claims 1 to 3,

a reference mark provided on the carriage,

the plurality of sensors are each configured to be capable of detecting a reference mark,

when the relative position of the reference mark with respect to a portion that becomes a reference of the position of the carriage is known,

the control device moves the carriage to cause one of the plurality of sensors to detect the reference mark, and determines the relative position of the carriage with respect to the reference sensor by using the sensor that detects the reference mark as the reference sensor.

5. A method of operating a linear motor transport system, the linear motor transport system comprising: a carriage driven by a linear motor; a plurality of sensors arranged along a predetermined path; and a control device for controlling the linear motor to move the carriage along the path, wherein the method for operating the linear motor transport system comprises the steps of:

a reference sensor determination step of determining a reference sensor to be output for position determination of the carriage from among the plurality of sensors; and

a position determination step of repeatedly determining a position of the carriage based on an output from the reference sensor,

the position determining step includes the step of switching the reference sensor among the plurality of sensors along with the movement of the carriage.

Technical Field

The invention relates to a linear motor conveying system and an application method thereof.

Background

Conventionally, as a conveying system for conveying an article, a linear motor conveying system is known in which a carriage is moved by using a linear motor as a drive source, and the article is conveyed by the carriage. The linear motor conveying system is provided with: a bracket: holding an article to be conveyed; a movable element of the linear motor mounted on the bracket; a stator of a linear motor including a plurality of electromagnets (coil units) arranged along a path; and a control device for controlling the current supply to the electromagnets to move the carriage along the path, and for conveying the article held by the carriage by moving the movable member along the path.

While conventional conveyor belts convey conveyed articles (i.e., articles) in the same direction at a constant speed, linear motor conveyor systems are capable of individually controlling the movement of a plurality of carriages holding the articles. Further, the following control can be performed: to make the carriages stay exactly at the necessary place, or to change the speed, or to make only one carriage move in reverse, etc. Further, since the linear motor conveying system is driven by the linear motor, dust and the like are not generated as compared with a conveying system using another driving method, and therefore, cleaning is performed.

Therefore, the linear motor conveying system is widely used, for example, in a processing line for performing inter-process conveyance and precision processing on a conveying path.

In the linear motor conveying system, in order to control the position of the movable member, it is necessary to continuously grasp the position of the movable member with respect to the stator. Conventionally, a linear motor conveying system has been proposed in which a sensor provided on a movable element side reads a linear scale provided on a stator side to detect a position of the movable element (for example, patent document 1).

Patent document 1: japanese patent laid-open publication No. 2014-219296

In the conventional linear motor conveyance system described in patent document 1, since the sensor is provided on the mover side, a battery for supplying power to the sensor needs to be provided on the mover side, and maintenance thereof is required. Further, since wiring for outputting the detection result of the sensor needs to be drawn from the movable element side, the movable range of the movable element is limited.

Disclosure of Invention

The present invention has been made in view of such circumstances, and an exemplary object of one embodiment thereof is to provide a linear motor conveyance system that improves the commercial value.

In order to solve the above problem, a linear motor conveyance system according to an embodiment of the present invention includes: a carriage driven by a linear motor; a plurality of sensors arranged along a predetermined path; and a control device for controlling the linear motor to move the carriage along the path. The control device switches a reference sensor, which uses an output for position determination of the carriage, among the plurality of sensors, as the carriage moves.

Another embodiment of the invention is a method of using a linear motor delivery system. In the method, the linear motor transport system includes: a carriage driven by a linear motor; a plurality of sensors arranged along a predetermined path; and a control device for controlling the linear motor to move the carriage along the path, the method of using the linear motor transport system comprising the steps of: a reference sensor determination step of determining a reference sensor that uses a detection result for position determination of the carriage from among the plurality of sensors; and a position determining step of repeatedly determining the position of the carriage based on the output from the reference sensor. The position determining step includes the step of switching the reference sensor among the plurality of sensors along with the movement of the carriage.

Any combination of the above-described constituent elements or a mode in which the constituent elements and expressions of the present invention are replaced with each other in a method, an apparatus, a system, or the like is also effective as an embodiment of the present invention.

According to the present invention, a linear motor conveyance system capable of improving the commercial value can be provided.

Drawings

Fig. 1 is a plan view of a linear motor transport system according to an embodiment.

Fig. 2 is a side view showing the bracket of fig. 1 and its periphery.

Fig. 3 is a side view showing the bracket of fig. 1 and its periphery.

Fig. 4 is a side view showing the bracket of fig. 1 and its periphery.

In the figure: 10-carriage, 12-linear motor, 18-sensor, 20-control device, 100-linear motor delivery system.

Detailed Description

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiments are not intended to limit the present invention, and are merely examples, and all the features and combinations described in the embodiments are not necessarily essential to the present invention. In the drawings, the same or equivalent constituent elements, components, and processes are denoted by the same reference numerals, and overlapping description thereof will be omitted as appropriate.

Fig. 1 is a plan view showing a schematic configuration of a linear motor conveyance system 100 according to an embodiment. Fig. 2 is a side view showing the carriage 10 of the linear motor conveying system 100 and its periphery.

The linear motor conveyance system 100 includes: a carrier 10 for holding an article to be conveyed; a linear motor 12 driving the carriage 10; a reference mark 14 and a linear scale 16 fixed to the carriage 10; a plurality of sensors 18 arranged along the conveyance path P of the carriage 10; and a control device 20 for controlling the linear motor conveying system 100 in a centralized manner. The plurality of sensors are wired to the control device 20. In addition, for the sake of easy understanding, only one bracket 10 is shown in fig. 1, but the present invention is not limited thereto, and a plurality of brackets 10 are generally provided.

The linear motor 12 includes a stator 22 and a mover 24 attached to the bracket 10.

In the present embodiment, the stator 22 is formed in a rectangular shape that is long in the D direction in a plan view. The stator 22 includes a plurality of electromagnets (coil units) 26 arrayed in the extending direction thereof. In fig. 1, only a portion of the electromagnets 26 are shown as an example. The power source 34 can supply current to each of the plurality of electromagnets 26. The arrangement of the plurality of electromagnets 26 determines the path P. In the present embodiment, the path P is a straight line, but is not particularly limited.

The movable member 24 is mounted on the lower surface of the carriage 10 so as to be vertically opposed to the electromagnet 26. The movable element 24 includes a magnet. Movable member 24 moves along path P by the interaction between the magnetic field of electromagnet 26 and the magnetic field of the magnet of movable member 24.

The stator 22 may be provided with a linear guide for guiding the movement of the movable member 24 or the carriage 10. Alternatively, the movable member 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, and if the sensor 18 is a magnetic sensor, the reference mark 14 is a magnet, and if the sensor 18 is an optical sensor, the reference mark 14 is, for example, a glass or steel tape marked with a mark.

Here, the reference mark 14 is provided on the lower surface of the carriage 10. In addition, the reference mark 14 may also be provided on the linear scale 16. The reference mark 14 is preferably arranged such that its position in the direction D coincides with the "position reference" of the carriage 10. The position reference portion is a portion that becomes a reference of the position of the carriage 10 in the D direction, and a typical position reference portion is a central portion of the carriage 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 portion in the D direction, the absolute position of the reference mark 14 becomes the absolute position of the carriage 10.

The reference mark 14 may be provided at any position of the carriage 10, but it is necessary to know the relative position thereof with respect to the position reference portion in advance. When the position of the reference mark 14 in the D direction does not coincide with the position of the position reference portion in the D direction, the absolute position of the carriage 10 is determined in consideration of the distance in the D direction between the position reference portion and the reference mark 14 on the basis of the absolute position of the reference mark 14.

Hereinafter, for simplification of the description, the position of the visual reference mark 14 in the D direction coincides with the position of the position reference portion in the D direction.

A linear scale 16 is fixed to the lower surface of the carriage 10. The linear scale 16 is not particularly limited, and if the sensor 18 is a magnetic sensor, the linear scale 16 is a magnet scale, and if the sensor 18 is an optical sensor, the linear scale 16 is, for example, a graduated glass scale or a steel tape. The linear scale 16 is provided on the carriage 10 such that the center of the linear scale 16 in the D direction coincides with the position of the positional reference of the carriage 10 in the D direction.

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 active area 16a is an area where the sensor 18 can read the scale, and the inactive area 16b is an area where the sensor 18 cannot read the scale.

The sensor 18 includes a 1 st detection unit 28 capable of detecting the reference mark 14 and a 2 nd detection unit 29 capable of detecting the linear scale 16. In the present embodiment, the sensor 18 is disposed such that the 1 st detecting section 28 is located on the moving path of the reference mark 14 and the 2 nd detecting section 29 is located on the moving path of the linear scale 16 in a plan view.

When the 1 st detection unit 28 detects the reference mark 14 (that is, when the reference mark 14 passes directly above the 1 st detection unit 28), a pulse signal having a predetermined intensity or more is output to the control device 20. The pulse width of the pulse signal is preferably equal to the resolution of the 1 st detection unit 28, but may be longer than this. As will be described in detail later, the control device 20 determines whether the reference mark 14 is positioned directly above the 1 st detecting unit 28 based on the output signal of the 1 st detecting unit 28.

The 2 nd detecting section 29 reads the scale provided on the linear scale 16 moving above the 2 nd detecting section 29, and outputs a pulse signal of 1 pulse to the control device 20 every time the linear scale 16 moves R [ μm ] (R is the resolution of the 2 nd detecting section 29) even for the carriage 10. The control device 20 counts the pulse signals output from the 2 nd detection unit 29 to determine (detect) the position of the carriage 10 in the D direction as described later.

The plurality of sensors 18 are arranged at equal intervals (here, intervals S). The plurality of sensors 18 are arranged such that the length of the effective region 16a of the linear scale 16 (hereinafter referred to as "effective region length") Le and the interval S between the sensors 18 satisfy the relationship "effective region length Le ≧ interval S". In this case, the effective region 16a of the linear scale 16 is located in the detection region of any one of the sensors 18 (i.e., directly above the sensor 18) regardless of the position of the carriage 10 on the path P, and therefore the absolute position of the carriage 10 can be determined as described below. If the effective region length Le is equal to the interval S, the number of sensors can be minimized. In summary, the absolute position of each of the plurality of sensors 18 is known.

Fig. 3 and 4 are side views showing the carriage 10 of the linear motor transport system 100 and the periphery thereof. In fig. 3, the reference mark 14 is located directly above the sensor 18. In fig. 4, the linear scale 16 is located even in the middle of the carriage 10 between two adjacent sensors. The control device 20 will be described with reference to fig. 1 to 4.

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

When a signal having a threshold intensity or higher is output from the 1 st detection unit 28 of any one of the sensors 18_1 to 18_ N (N is an integer of 2 or higher, and N is 5 or higher in the example of fig. 2 to 4) (specifically, for example, a signal having a threshold intensity or higher is output from the 1 st detection unit 28 of the sensor 18_ i), the position specifying unit 30 specifies that the reference mark 14 or even the carriage 10 is positioned directly above the sensor 18_ i. The position specifying unit 30 specifies the sensor 18_ i that detects the reference mark 14 as a sensor (hereinafter, referred to as a "reference sensor") serving as a reference for specifying the absolute position of the carriage 10.

The position specifying unit 30 sets "0" when the reference mark 14 is positioned directly above the reference sensor, and counts the pulse signal output from the 2 nd detecting unit 29 of the reference sensor in accordance with the movement of the carriage 10.

The position determining part 30 determines the distance of the carriage 10 from the reference sensor (i.e., the relative position of the carriage 10 with respect to the reference sensor) based on the count value of the pulse signal output from the 2 nd detecting part 29 of the reference sensor. The position specifying unit 30 adds the specified relative position to the absolute position of the reference sensor to specify the absolute position of the carriage 10.

However, depending on the length of the linear scale 16, if the carriage 10 moves a certain distance, the effective area 16a of the linear scale 16 may be out of the detection range (i.e., directly above) of the 2 nd detection part 29 of the reference sensor. In this way, the position of the carriage 10 cannot be determined from the output of the reference sensor. Therefore, the sensor 18 adjacent to the reference sensor and within the effective region 16a of the linear scale 16 in the detection range (i.e., immediately above) thereof needs to be set as a new reference sensor before the effective region 16a of the linear scale 16 is out of the detection range of the reference sensor. That is, the reference sensor needs to be switched.

Specifically, for example, when the sensor 18_ i is a reference sensor, if the carriage 10 moves to the right side of the paper surface in the D direction and the relative position (the count value of the pulse signal) of the carriage 10 with respect to the sensor 18_ i becomes a predetermined value, the position determination unit 30 sets the adjacent sensor 18_ i +1 as a new reference sensor. Therefore, before switching the reference sensor, the position determining part 30 determines the absolute position of the carriage 10 by determining the relative position of the carriage 10 with respect to the sensor 18_ i, but after switching the reference sensor, determines the absolute position of the carriage 10 by determining the relative position of the carriage 10 with respect to the sensor 18_ i + 1. That is, the absolute position of the carriage 10 is determined by adding the absolute position of the sensor 18_ i +1 to the relative position of the carriage 10 with respect to the sensor 18_ i + 1.

In addition, at the time of switching the reference sensor, the relative position of the carriage 10 with respect to the sensor 18 after switching is determined based on the relative position of the carriage 10 with respect to the sensor 18_ i before switching. In other words, at the time of switching the reference sensor, the initial value of the count value of the pulse signal in the sensor 18_ i +1 after the switching is determined from the count value of the pulse signal in the sensor 18_ i before the switching. After that, the count value of the pulse signal output from the sensor 18_ i +1 is accumulated on the basis of the determined initial value.

As for the switching of the reference sensor, for example, as shown in fig. 4, it may be performed at a timing at which the center of the linear scale 16 (the center of the carriage 10 in this example) reaches the middle between the reference sensor (the sensor 18_ i in this example) and the sensor adjacent to the reference sensor (the sensor 18_ i +1 in this example).

In this case, when the carriage 10 moves forward to the right side in the direction D in fig. 1 to 4, the position specifying unit 30 may switch the reference sensor when the count value (CNT) of the output of the pulse signal from the 2 nd detecting unit 29 of the reference sensor becomes a value obtained by the following expression (1). Here, in fig. 1 to 4, the direction toward the right in the D direction is a positive direction, and the direction toward the left is a negative direction.

CNT＝+1/2×(Ls-2X-2Y)×1/{R×1/1000}……(1)

Wherein the content of the first and second substances,

ls: length [ mm ] in the D direction of the linear scale 16;

x: a length [ mm ] in the D direction of the ineffective area 16b existing at both ends of the linear scale 16;

y: the distance [ mm ] of the reference sensor from the invalid region 16b before switching when switching the reference sensor;

r: the resolution of the sensor 18 (1 count R μm).

The position specifying unit 30 sets the count value (CNT) obtained in the following expression (2) as the initial value of the count value of the pulse signal output from the 2 nd detecting unit 29 of the new reference sensor in accordance with the movement of the carriage 10. That is, after the reference sensor is switched, the pulse signal output from the 2 nd detection unit 29 of the new reference sensor is counted from the count value obtained by the equation (2).

CNT＝-1/2×(Ls-2X-2Y)×1/{R×1/1000}……(2)

In fig. 1 to 4, when the carriage 10 moves to the left side in the direction D (i.e., in the negative direction), the positive and negative of the expressions (1) and (2) may be reversed.

As described above, the position specifying unit 30 switches the reference sensor in accordance with the movement of the carriage 10 and continuously and repeatedly specifies the absolute position of the carriage 10.

The linear motor control section 32 controls the linear motor 12 to move the carriage 10. Specifically, the linear motor control unit 32 controls the supply of electric current from the power source 34 to each electromagnet 26 of the stator 22 so as to move the carriage 10 to a desired position while feeding back the positional information of the carriage 10 specified by the position specifying unit 30.

The above is the basic structure of the linear motor conveyor system 100. Next, the operation of the linear motor transport system 100 will be described with reference to fig. 2 to 4. The time passes in the order of fig. 2, fig. 3, fig. 4.

The state when the linear motor conveyance system 100 is started is assumed to be the state of fig. 2. The control device 20 causes a constant current to flow to the electromagnet 26 to move the carriage 10. Thereby, the carriage 10 moves to the right in fig. 2.

In fig. 3, the carriage 10 reaches directly above the sensor 18_ i. The sensor 18_ i detects the reference mark 14. Therefore, the sensor 18_ i becomes a reference sensor. The control device 20 determines the absolute position of the carriage 10 based on the count value of the pulse signal output from the reference sensor.

In fig. 4, the relative position of the carriage 10 with respect to the sensor 18_ i (i.e., the count value of the pulse signal in the sensor 18_ i) becomes the value obtained by the equation (1), and therefore the reference sensor is switched from the sensor 18_ i to the sensor 18_ i + 1.

Next, the effects of the embodiment will be described. According to the present embodiment, since the position of the bracket 10 can be detected by the sensor 18 provided on the stator 22 side, it is not necessary to provide a sensor on the bracket 10 side for detecting the position of the bracket 10, and therefore, it is not necessary to mount a battery on the bracket 10 or draw out a wire from the bracket 10.

Further, according to the present embodiment, even if the length of the linear scale 16 changes due to a change in the size of the carriage 10 or even if the resolution of the sensor 18 changes, it is only necessary to change the values in expressions (1) and (2), and therefore such a change can be easily coped with.

The present invention has been described above with reference to the embodiments. The embodiment is an example, and those skilled in the art will understand that various modifications exist in the combination of these respective constituent elements and the respective processing steps, and that such modifications also fall within the scope of the present invention. Hereinafter, a modified example will be described.

In the embodiment, the case where the plurality of sensors 18 are arranged at equal intervals has been described, but as long as the interval between the adjacent sensors 18 is equal to or less than the effective region length Le of the linear scale 16, the interval between the adjacent sensors 18 may not be equal. That is, at least one sensor spacing may be different from other sensor spacings. In this case, although the count value may be different when the sensors 18 are switched, when the reference sensor is switched at a timing when the center of the linear scale 16 (the center of the carriage 10 in this example) reaches the middle between the adjacent sensors 18, the sensor 18 may be switched at a timing when the count value before the switching becomes the count value obtained by equation (1).

Any combination of the above-described embodiment and the modification is also effective as an embodiment of the present invention. The new embodiment which is produced by the combination has the effects of both the combined embodiment and the modified example.