Magnetic levitation device, control method for magnetic levitation device, manufacturing system and method of manufacturing article

Abstract

To provide a magnetic levitation device capable of stably levitating a movable element even if the movable element is large-sized and the rigidity thereof is low, and a control method for a movable element.SOLUTION: A magnetic levitation device comprises: a movable element including a first magnetic force part; a second magnetic force part which is provided at a position opposite the first magnetic force part and causes a magnetic force to act between the second magnetic force part and the first magnetic force part; a guide part which supports the movable element; and a control part which controls a position and an attitude of the movable element. One of the first magnetic force part and the second magnetic force part includes a coil and the other includes a permanent magnet. The control part controls a current to flow to the coil, thereby controlling the position and the attitude of the movable element. The control part levitates the movable element from the guide part by starting position control to the movable element in a levitation direction in which the movable element is levitated from the guide part while the movable element is in contact with the guide part and starting zero power control to the movable element while the movable element is in contact with the guide part after the position control.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a magnetic levitation device, a control method for a magnetic levitation device, a manufacturing system, and a method for manufacturing an article. [Background technology]

[0002] Conveyance devices are generally used in production lines for assembling industrial products, semiconductor exposure equipment, and the like. Conveyance devices in production lines, in particular, transport workpieces such as parts between multiple stations within a factory-automated production line or between production lines. Conveyance devices may also be used as transport means within process equipment. Conveyance devices using moving magnet linear motors have already been proposed.

[0003] Conveyance devices using moving magnet linear motors use guide devices that involve mechanical contact, such as linear guides. However, conveyance devices using guide devices such as linear guides have the problem of reduced productivity due to contaminants generated from the sliding parts of the linear guide, such as wear debris from rails and bearings, lubricating oil, and volatilized lubricating oil. Another problem is that friction in the sliding parts increases during high-speed conveyance, shortening the lifespan of the linear guide.

[0004] Therefore, Patent Document 1 describes a magnetic levitation conveyance device capable of conveying a mover in a non-contact manner. In the magnetic levitation conveyance device described in Patent Document 1, the mover is levitated and conveyed by an electromagnetic force generated by passing a current through a group of permanent magnets arranged along the conveyance direction of the mover and a group of coils facing the permanent magnets and the coils.

[0005] Furthermore, in general, in a magnetic levitation transport device, a zero power control method is known in which the coil current value is controlled to converge to near zero in order to reduce the power consumption for supporting the mover in a non-contact manner.

[0006] For example, Patent Document 2 describes a method of mounting a gap sensor that detects a predetermined gap between the mover and the magnetic support unit, and controlling the current of the electromagnet so that the gap length is maintained so that the weight of the mover and the attractive force of the permanent magnet are in perfect balance. That is, Patent Document 2 describes a method of controlling levitation by setting the gap length of the mover so that the excitation current of the electromagnet is zero.

[0007] In the zero-power control method, control is performed so that the current flowing through the coil becomes zero. For this reason, the zero-power control method cannot be used when the mover is in contact with the guide and supported by the guide, such as when the power is off. Therefore, when transitioning the mover from a contact state with the guide to a non-contact state, it is necessary to issue a position command in the levitation direction by controlling the gap length to be constant. In Patent Document 2, the reaction force from the guide that supports the mover in contact is estimated, and the transition to the non-contact state is confirmed by detecting that the estimated reaction force value has become zero or a relatively small value, and then the zero-power control is switched to. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2020-28212 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-125067 Summary of the Invention [Problem to be solved by the invention]

[0009] However, when controlling a large, low-rigidity mover in the levitation control method described in Patent Document 2, the mover may oscillate due to its natural vibration or resonance with the guide when transitioning to a non-contact state, which is a levitated state. This poses a risk of impact on the transported object mounted on the mover or failure to transition the mover to a levitated state.

[0010] An object of the present invention is to provide a magnetic levitation device and a method for controlling a magnetic levitation device that can stably levitate a mover even if the mover is large and has low rigidity. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a magnetic levitation device comprising: a mover having a first magnetic force portion; a second magnetic force portion disposed opposite the first magnetic force portion and exerting a magnetic force between the first magnetic force portion and the second magnetic force portion; a guide portion supporting the mover; and a control portion for controlling the position and attitude of the mover, wherein one of the first magnetic force portion and the second magnetic force portion includes a coil and the other includes a permanent magnet, the control portion controls the position and attitude of the mover by controlling the current flowing through the coil, the control portion initiates position control of the mover in a levitation direction in which the mover levitates from the guide portion when the mover is in contact with the guide portion, and after the position control, initiates zero power control of the mover when the mover is in contact with the guide portion, thereby levitating the mover from the guide portion. [Effects of the Invention]

[0012] According to the present invention, even if the mover is large and has low rigidity, the mover can be levitated stably. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic view showing a conveying device according to a first embodiment of the present invention. [Figure 2] 1 is a schematic view showing a cross section of a conveying device according to a first embodiment of the present invention. [Figure 3] 1 is a schematic diagram showing a control system for controlling a transport device according to a first embodiment of the present invention. [Figure 4] 1 is a schematic diagram showing a coil and a configuration related to the coil in a transport device according to a first embodiment of the present invention. [Figure 5]3A and 3B are schematic diagrams illustrating a method for controlling the position and attitude of a mover in the transport device according to the first embodiment of the present invention. [Figure 6] 3 is a schematic diagram showing a control block for controlling the position and attitude of a mover in the transport device according to the first embodiment of the present invention. FIG. [Figure 7A] 4 is a Bode diagram showing an example of frequency characteristics of a mover in the transport device according to the first embodiment of the present invention. FIG. [Figure 7B] 4 is a Bode diagram showing an example of frequency characteristics of a mover in the transport device according to the first embodiment of the present invention. FIG. [Figure 8] 3A and 3B are schematic diagrams showing the attitude of a mover during a transition to levitation in the transport device according to the first embodiment of the present invention. [Figure 9A] 5 is a schematic diagram showing the relationship between the force in the Z direction acting on the mover and the position in the Z direction in the transport device according to the first embodiment of the present invention. FIG. [Figure 9B] 5 is a schematic diagram showing the relationship between the force in the Z direction acting on the mover and the position in the Z direction in the transport device according to the first embodiment of the present invention. FIG. [Figure 9C] 5 is a schematic diagram showing the relationship between the force in the Z direction acting on the mover and the position in the Z direction in the transport device according to the first embodiment of the present invention. FIG. [Figure 9D] 5 is a graph showing the relationship between the force acting on the mover in the Z direction and the position in the Z direction in the transport device according to the first embodiment of the present invention. [Figure 10] 6 is a graph showing transitions of the position of the mover in the Z direction and the position in the Wx direction during execution of levitation control in the transport device according to the first embodiment of the present invention. [Figure 11A] 5A and 5B are schematic diagrams showing transitions in the position and attitude of a mover during execution of levitation control in the transport device according to the first embodiment of the present invention. [Figure 11B] 5A and 5B are schematic diagrams showing transitions in the position and attitude of a mover during execution of levitation control in the transport device according to the first embodiment of the present invention. [Figure 11C] 5A and 5B are schematic diagrams showing transitions in the position and attitude of a mover during execution of levitation control in the transport device according to the first embodiment of the present invention. [Figure 12]FIG. 10 is a schematic diagram showing a control block for controlling the position and attitude of a mover in a transport device according to a second embodiment of the present invention. [Figure 13A] 10A and 10B are schematic diagrams showing transitions in the position and attitude of a mover during execution of levitation control in a transport device according to a second embodiment of the present invention. [Figure 13B] 10A and 10B are schematic diagrams showing transitions in the position and attitude of a mover during execution of levitation control in a transport device according to a second embodiment of the present invention. [Figure 13C] 10A and 10B are schematic diagrams showing transitions in the position and attitude of a mover during execution of levitation control in a transport device according to a second embodiment of the present invention. [Figure 13D] 10 is a graph showing the relationship of the spring constant at each position of the mover in the transport device according to the second embodiment of the present invention. [Figure 14] 10 is a flowchart showing a floating sequence of a mover in a transport device according to a second embodiment of the present invention. [Figure 15] FIG. 10 is a schematic diagram showing a rotation drive device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] [First embodiment] A magnetic levitation device according to a first embodiment of the present invention will be described with reference to Figures 1 to 11C. In this embodiment, a conveyance device will be described as an example of the magnetic levitation device.

[0015] First, the configuration of the conveying device 1 according to this embodiment will be described with reference to Figs. 1 to 4. Figs. 1 and 2 are schematic diagrams showing the configuration of the conveying device 1 including a mover 101 and a stator 201 according to this embodiment. Note that Figs. 1 and 2 show the main parts of the mover 101 and the stator 201, respectively. Fig. 1 is a view of the mover 101 seen from diagonally above. Fig. 2 is a cross-sectional view of the mover 101 and the stator 201 seen from the X direction, which will be described later. Fig. 3 is a schematic diagram showing a coil 202 and a configuration related to the coil 202. Fig. 4 is a schematic diagram showing a control system 3 in the conveying device 1.

[0016] 1 and 2, the conveying device 1 according to this embodiment has a mover 101 that constitutes a carrier that conveys workpieces, and a stator 201 that constitutes a conveying path. Note that in FIG. 1, two movers 101a and 101b are shown as the movers 101. The conveying device 1 also has an integrated controller 301, a coil controller 302, a coil unit controller 303, and a sensor controller 304. Hereinafter, when there is no need to particularly distinguish between components that may be present in plurality, such as movers 101 and stators 201, common numerals only will be used, and lowercase letters will be added after the numerals to distinguish between them as necessary.

[0017] The conveyance device 1 according to this embodiment is a linear motor-based conveyance device that conveys the mover 101 by generating an electromagnetic force between the permanent magnet 103 of the mover 101 and the coil 202 of the stator 201. The conveyance device 1 according to this embodiment is also a magnetic levitation type conveyance device that levitates the mover 101 and conveys it in a non-contact manner. In the conveyance device 1, the permanent magnet 103 of the mover 101 and the coil 202 of the stator 201 function as a magnetic force section in which a magnetic force acts between them.

[0018] The conveyance device 1 according to this embodiment constitutes part of a manufacturing system that also includes process equipment for performing operations such as machining and inspection on the workpiece conveyed by the mover 101. Generally, conveyance devices are used in production lines for assembling industrial products, semiconductor exposure equipment, and the like. In particular, conveyance devices in production lines convey workpieces such as parts between multiple stations within a factory-automated production line or between production lines. They may also be used as conveyance devices in process equipment. The conveyance device 1 according to this embodiment can be used for such applications.

[0019] The transport device 1 transports the workpiece held by the mover 101, for example, by transporting the mover 101 using the stator 201, to a process device that performs an operation on the workpiece. The process device is not particularly limited, but is, for example, a film formation device such as a vapor deposition device or a sputtering device that forms a film on a substrate 102, which is the workpiece, as described below. The manufacturing system manufactures an article by performing an operation on the workpiece.

[0020] Here, we define the coordinate axes, directions, and the like used in the following description. First, the X-axis is taken along the horizontal direction, which is the transport direction of the mover 101, and the transport direction of the mover 101 is taken as the X-direction. The Z-axis is taken along the vertical direction, which is perpendicular to the X-direction, and the vertical direction is taken as the Z-direction. The vertical direction is the direction of gravity (mg direction). The Y-axis is taken along the direction perpendicular to the X-direction and the Z-direction, and the direction perpendicular to the X-direction and the Z-direction is taken as the Y-direction. The X-direction and the Y-direction are horizontal directions. Furthermore, rotation around the X-axis is taken as Wx, the rotation around the Y-axis is taken as Wy-direction, and the rotation around the Z-axis is taken as Wz-direction. Furthermore, as the displacement of the mover 101 in each direction, the position in the X-direction is taken as X, the position in the Y-direction is taken as Y, and the position in the Z-direction is taken as Z. Furthermore, as the rotation amount, which is the displacement of the mover 101 in each rotation direction, the rotation amount in the Wx-direction is taken as Wx, the rotation amount in the Wy-direction is taken as Wy, and the rotation amount in the Wz-direction is taken as Wz. Furthermore, a "*" is used as a multiplication symbol. Furthermore, the center of the mover 101 is defined as the origin Oc, and the +Y side is defined as the L side and the -Y side is defined as the R side. When distinguishing between components located on the L side and components located on the R side, the numerals are followed by L, indicating that the component is located on the L side, or R, indicating that the component is located on the R side, to distinguish between the two. Note that the transport direction of the mover 101 does not necessarily have to be the horizontal direction, but in that case, the transport direction can also be defined as the X direction, and the Y direction and Z direction can be similarly defined. Furthermore, the X direction, Y direction, and Z direction are not necessarily limited to directions perpendicular to each other, and can also be defined as directions intersecting each other.

[0021] 1, the mover 101 is configured to be movable along the X direction, which is the transport direction. The mover 101 has a permanent magnet 103, a linear scale 104, a Y target 105, a Z target 106, and a stopper 107. The mover 101 has an upper surface and a lower surface located opposite the upper surface.

[0022] A plurality of permanent magnets 103 are attached and installed along the X direction at each end of the R-side and L-side on the top surface of the mover 101. The multiple permanent magnets 103 constituting the magnet groups on each of the R-side and L-side include multiple XZ magnet groups and multiple Y magnet groups. The XZ magnet group is a magnet group arranged so that different magnetic poles, N poles and S poles, are alternately arranged in the X direction. The Y magnet group is a magnet group arranged so that different magnetic poles, N poles and S poles, are alternately arranged in the Y direction. The N poles and S poles described here refer to the polarities of the top surface of each permanent magnet 103. The installation location and number of permanent magnets 103 are not particularly limited and can be changed as appropriate. The permanent magnets 103 function as a magnetic force unit that exerts a magnetic force between the permanent magnets 103 and the coils 202 of the stator 201.

[0023] The linear scale 104, Y target 105, and Z target 106 are attached to the mover 101 at positions that allow reading by a linear encoder and a sensor, respectively, that are installed on the stator 201. The linear encoder and sensor referred to here include a linear encoder 204, a Y sensor 205, and a Z sensor 206, which will be described later.

[0024] The stoppers 107 are attached and installed so as to protrude outward in the Y direction from both side surfaces of the mover 101 facing the Y direction. An upper guide 207 and a lower guide 208, which will be described later, are installed to face the stoppers 107 from above and below in the Z direction.

[0025] The stator 201 includes a coil 202 , a linear encoder 204 , a Y sensor 205 , a Z sensor 206 , an upper guide 207 , and a lower guide 208 .

[0026] A plurality of coils 202 are attached to the stator 201 along the X direction at positions facing the permanent magnets 103 installed on the upper surface of the mover 101. Specifically, the plurality of coils 202 are arranged in two rows along the X direction so as to face from above along the Z direction two permanent magnets 103 installed at the ends of the R side and the L side on the upper surface of the mover 101. The installation locations and number of coils 202 are not particularly limited and can be changed as appropriate. The coils 202 function as a magnetic force portion that generates a magnetic force between the coils 202 and the permanent magnets 103 of the mover 101.

[0027] When a current is applied to each coil 202 of the stator 201, an electromagnetic force is generated between the coil 202 and the permanent magnet 103. This allows the mover 101 to move in the X direction while floating in the Z direction. The coil 202 has a magnetic core, and the magnetic attractive force acting between the core and the permanent magnet 103 assists the upward force acting on the mover 101.

[0028] The linear encoder 204, the Y sensor 205, and the Z sensor 206 function as detection units that detect the position and posture of the mover 101 as it moves along the transport direction.

[0029] The linear encoder 204 is attached to the stator 201 so as to be able to read the linear scale 104 attached to the mover 101. The linear encoder 204 detects the relative position of the mover 101 with respect to the linear encoder 204 by reading the linear scale 104. The linear encoder 204 reads the linear scale 104 attached to the mover 101.

[0030] The Y sensor 205 is attached to the stator 201 so as to be able to detect the distance in the Y direction from the Y target 105 attached to the mover 101. The Z sensor 206 is attached to the stator 201 so as to be able to detect the distance in the Z direction from the Z target 106 attached to the mover 101.

[0031] The upper guide 207 and the lower guide 208 are attached to the stator 201 along the X direction so as to face the stopper 107 attached to the mover 101 from above and below in the Z direction. A plurality of upper guides 207 and lower guides 208 are installed. The upper guide 207 is installed so as to face the stopper 107 from above. The lower guide 208 is installed so as to face the stopper 107 from below. The upper guide 207 and the lower guide 208 are guide portions that come into contact with the stopper 107 depending on the position of the mover 101 in the Z direction and regulate the movable range of the mover 101 in the Z direction. When the mover 101 is not levitated, such as when the conveyance device 1 is powered off, the mover 101 is attracted to the upper guide 207 by the magnetic attraction force of the permanent magnet 103, or comes into contact with and is supported by the lower guide 208. The upper guide 207 or the lower guide 208 comes into contact with the mover 101 when it is not levitated, and supports the mover 101 .

[0032] The mover 101 is designed to transport a workpiece attached or held, for example, above or below the mover 101. Note that Fig. 2 shows a state in which a substrate 102 such as a glass substrate as the workpiece is held by a holding mechanism 108 provided on the underside of the mover 101. The mechanism for attaching or holding the workpiece to the mover 101 is not particularly limited, and general attachment mechanisms, holding mechanisms, etc., such as a mechanical hook or an electrostatic chuck, can be used.

[0033] 2 also shows a film forming device 7 that forms a film by vapor deposition or the like on a substrate 102 held by the mover 101, as an example of a process device that performs processing or other operations on a workpiece held by the mover 101. The film forming device 7 is incorporated into the stator 201 and installed. The transport device 1 and the film forming device 7 constitute a manufacturing system.

[0034] The film forming apparatus 7 has a pattern mask 501 installed so as to face the substrate 102 held below the mover 101, and a film forming source 701 installed below the pattern mask 501 so as to face the substrate 102 with the pattern mask 501 interposed therebetween. The film forming source 701 is a film forming source that emits a film forming material for forming a film on the substrate 102. The pattern mask 501 is, for example, a mask foil provided with a predetermined opening pattern to be formed in the film to be formed. As the mover 101 is transported in the X direction, the substrate 102 held by the mover 101 stops in a state where it is floating above the pattern mask 501.

[0035] After the mover 101 floats and stops at a predetermined position in the X direction and the substrate 102 and the pattern mask 501 are aligned, a film forming material is released from the film forming source 701 arranged below the pattern mask 501 to form a film on the substrate 102. In this way, the workpiece is transported together with the mover 101, and the transported workpiece is processed by the process device to manufacture an article from the workpiece. Note that the process device is not limited to the film forming device 7, and may be a device that performs a process on the workpiece in accordance with the workpiece transported by the mover 101.

[0036] Next, the control system 3 that controls the conveying device 1 according to this embodiment will be described with reference to Fig. 3 and Fig. 4. The control system 3 can constitute a part of the conveying device 1. Fig. 3 is a schematic diagram showing the control system 3 that controls the conveying device 1 according to this embodiment. Fig. 4 is a schematic diagram showing the connection configuration of the coil controller 302.

[0037] 3, the control system 3 includes an integrated controller 301, a coil controller 302, and a sensor controller 304. The control system 3 functions as a control unit that controls the conveyance device 1 including the mover 101 and the stator 201. The coil controller 302 and the sensor controller 304 are communicatively connected to the integrated controller 301.

[0038] A plurality of coil unit controllers 303 are communicatively connected to the coil controller 302. The coil controller 302 and the plurality of coil unit controllers 303 connected thereto are provided corresponding to the respective columns of the coils 202. Each coil unit controller 303 is connected to a coil 202.

[0039] 4, one or more coils 202 are connected to each coil unit controller 303. A current sensor 312 and a current controller 313 are connected to the coils 202. The current sensor 312 detects the value of a current flowing through the connected coil 202. The current controller 313 controls the amount of current flowing through the connected coil 202. In this way, the coil unit controller 303 controls the amount of current through the connected coil 202.

[0040] The coil unit controller 303 commands the current controller 313 to control the desired amount of current based on the current command value received from the coil controller 302. The current controller 313 detects the current value detected by the current sensor 312 and controls the amount of current so that the desired amount of current flows through the coil 202.

[0041] A plurality of linear encoders 204, a plurality of Y sensors 205, and a plurality of Z sensors 206 are communicatively connected to the sensor controller 304.

[0042] The multiple linear encoders 204 are attached to the stator 201 at intervals such that one of them can always measure the position of one mover 101 even while the mover 101 is being transported. The multiple Y sensors 205 are attached to the stator 201 at intervals such that two of them can always measure the Y target 105 of one mover 101. The multiple Z sensors 206 are attached to the stator 201 at intervals and in a plane such that three of the two rows can always measure the Z target 106 of one mover 101.

[0043] Based on the outputs from the linear encoder 204, the Y sensor 205, and the Z sensor 206, the integrated controller 301 determines current command values ​​to be applied to the multiple coils 202 and transmits them to the coil controller 302. Based on the current command values ​​from the integrated controller 301, the coil controller 302 issues current value commands to the coil unit controller 303 as described above. In this way, the integrated controller 301 functions as a control unit, transports the mover 101 along the stator 201 in a non-contact manner, and controls the attitude of the transported mover 101 in six axes.

[0044] Next, a method for controlling the position and attitude of the mover 101 executed by the integrated controller 301 will be described with reference to FIG. 5. FIG. 5 is a schematic diagram showing a method for controlling the position and attitude of the mover 101 in the transportation device 1 according to this embodiment. FIG. 5 shows an outline of the method for controlling the attitude of the mover 101, focusing mainly on the data flow. As will be described below, the integrated controller 301 executes processing using a mover position calculation function 401, a mover attitude calculation function 402, a mover attitude control function 403, and a coil current calculation function 404. In this way, the integrated controller 301 controls the transportation of the mover 101 while controlling the attitude of the mover 101 in six axes. Note that instead of the integrated controller 301, the coil controller 302 can be configured to execute processing similar to that of the integrated controller 301.

[0045] First, mover position calculation function 401 calculates the number and positions of movers 101 on stators 201 that form the conveyance path from measurement values ​​from multiple linear encoders 204 and information on their mounting positions. As a result, mover position calculation function 401 updates mover position information (X) and number information of mover information 406, which is information on the movers 101. Mover position information (X) indicates the position of mover 101 on stator 201 in the X direction, which is the conveyance direction. Mover information 406 is prepared for each mover 101 on stator 201, as shown by POS-1, POS-2, ... in FIG. 5, for example.

[0046] Next, mover posture calculation function 402 identifies Y sensors 205 and Z sensors 206 capable of measuring each mover 101 from the mover position information (X) of mover information 406 updated by mover position calculation function 401. Next, mover posture calculation function 402 calculates posture information (Y, Z, Wx, Wy, Wz), which is information about the posture of each mover 101, based on the values ​​output from the identified Y sensors 205 and Z sensors 206, and updates mover information 406. Mover information 406 updated by mover posture calculation function 402 includes mover position information (X) and posture information (Y, Z, Wx, Wy, Wz).

[0047] Next, mover attitude control function 403 calculates applied force information 408 for each mover 101 from current mover information 406, including mover position information (X) and attitude information (Y, Z, Wx, Wy, Wz), and the target attitude value. Applied force information 408 is information regarding the magnitude of the force to be applied to each mover 101. Applied force information 408 includes information regarding the three-axis force components (Tx, Ty, Tz) and three-axis torque components (Twx, Twy, Twz) of an applied torque Tq to be applied (described later). Applied force information 408 is prepared for each mover 101 on the stator 201, as shown by TRQ-1, TRQ-2, ... in FIG. 5. Note that in this specification, torque includes both force and force moment, and torque in a direction along an axis, such as the X, Y, or Z direction, refers to a force.

[0048] Here, the three-axis components of the force, Tx, Ty, and Tz, are the X-direction component, Y-direction component, and Z-direction component of the force, respectively. Furthermore, the three-axis components of the torque, Twx, Twy, and Twz, are the X-axis component, Y-axis component, and Z-axis component of the torque, respectively. The conveyance device 1 according to this embodiment controls the six-axis components (Tx, Ty, Tz, Twx, Twy, and Twz) of the applied torque Tq, thereby controlling the posture of the mover 101 in six axes and controlling the conveyance of the mover 101.

[0049] Next, the coil current calculation function 404 determines a current command value 409 to be applied to each coil 202 based on the applied force information 408 and the mover information 406 .

[0050] In this way, the integrated controller 301 executes processing using the mover position calculation function 401, the mover attitude calculation function 402, the mover attitude control function 403, and the coil current calculation function 404, thereby determining the current command value 409. The integrated controller 301 transmits the determined current command value 409 to the coil controller 302.

[0051] In this way, the integrated controller 301 controls the current flowing through the coil 202, thereby controlling the position and attitude of the mover 101 in the X, Y, Z, Wx, Wy, and Wz directions.

[0052] The control of the position and attitude of the mover 101 will be described in further detail with reference to Fig. 6. Fig. 6 is a schematic diagram showing a control block for controlling the position and attitude of the mover 101 in the transport device 1 according to this embodiment. The integrated controller 301 executes control using the control block shown in Fig. 6.

[0053] 6, P is the position and orientation of the mover 101, and has components (X, Y, Z, Wx, Wy, Wz). ref1 is a position command target value that commands the target value of (X, Y, Z, Wx, Wy, Wz). err is the deviation between the position command target value ref1 and the position and orientation P.

[0054] The mover attitude control function 403 calculates the desired torque Tq to be applied to the mover 101 from the magnitude of the deviation err, the change in the deviation err, the integrated value of the deviation err, and the like.

[0055] Based on the applied torque Tq and the position and attitude P, the coil current calculation function 404 calculates the desired coil current I to be applied to the coil 202 in order to apply the applied torque Tq to the mover 101. When the coil current I calculated in this way is applied to the coil 202, the applied torque Tq acts on the mover 101, and the position and attitude P of the mover 101 change again.

[0056] Furthermore, the integrated controller 301 can control the torque applied to the mover 101 by further executing processing using a torque control function 605. The torque control function 605 calculates the manipulated variable d toward the target value ref2 from the integrated value of the difference between the applied torque Tq and the command torque Trqref. The command torque Trqref has components Tx′, Ty′, Tz′, Twx′, Twy′, and Twz′, with respect to the six-axis components (Tx, Ty, Tz, Twx, Twy, Twz) of the applied torque Tq. Tx′ is the command value for Tx, Ty′ is the command value for Ty, Tz′ is the command value for Tz, Twx′ is the command value for Twx, Twy′ is the command value for Twy, and Twz′ is the command value for Twz. The mover attitude control function 403 can calculate the applied torque Tq to be applied to the mover 101 taking the manipulated variable d into consideration. Here, by setting Tz', Twx', and Twy', among the components of the command torque Trqref, to zero, it is possible to execute so-called zero power control in the Z direction, Wx direction, and Wy direction. By using zero power control, it is possible to control the levitation of the mover 101 at a position and attitude where the gravity and the attractive force acting on the mover 101 are balanced. In this embodiment, the integrated controller 301 always sets Tz', Twx', and Twy', among the components of the command torque Trqref, to zero, and can use the torque control function 605 as a function for zero power control.

[0057] Furthermore, the integrated controller 301 uses a switch 606 as switching means for switching between position control and zero power control as control for the mover 101. The position control controls the position and attitude of the mover 101 so that they become predetermined target values. The switch 606 outputs a value of 0 or an operation amount d calculated by the torque control function 605 based on the value of the position command target value ref1. The output of the switch 606 is added to the position command target value ref1. As a result, the target values ​​for the position and attitude of the mover 101 are updated from ref1 to ref2.

[0058] 6 controls the position and attitude of the mover 101 by position control when the output of the switch 606 is a value of 0, and controls the position and attitude of the mover 101 by zero power control when the output of the switch 606 is a manipulated variable d. By configuring the control block in this way, it becomes possible to control the position and attitude of the mover 101 to a desired position and attitude.

[0059] When transitioning the mover 101 supported by the lower guide 208 to a levitated state, simply transitioning the mover 101 to a levitated state by position control may result in oscillation of the mover 101. Here, the mechanism by which the mover 101 oscillates when transitioning the mover 101 to a levitated state by position control will be described with reference to Figures 7 and 8. Note that although the mechanism of oscillation will be described here using the Wx direction as an example, a similar phenomenon can occur in the Wy direction as well.

[0060] 7A and 7B are examples of Bode diagrams showing frequency characteristics in the Wx direction of the mover 101. The vertical axis of the graph shown in FIG. 7A is gain when the applied torque Tq is the input and the position and posture are the outputs. The gain indicates the amount of position fluctuation with respect to fluctuations in the applied torque Tq, and is calculated by (position P / applied torque Tq). The vertical axis of the graph shown in FIG. 7B is the difference between the phase of the applied torque Tq and the phase of the position P. The horizontal axis of the graphs shown in FIGS. 7A and 7B is frequency. In other words, the graphs shown in FIGS. 7A and 7B show the responsiveness of the position and posture of the mover 101 on the frequency axis.

[0061] The dashed lines in Figures 7A and 7B show an example of the frequency characteristics of mover 101 placed on lower guide 208. The solid lines in Figures 7A and 7B show an example of the frequency characteristics of mover 101 in a non-contact state, that is, mover 101 in a levitated state. f1 is the natural frequency of lower guide 208, and f2 is the natural frequency of mover 101. Near the natural frequency, the gain characteristics become large and the phase lag occurs, making mover 101 more likely to oscillate.

[0062] When the mover 101 transitions from a state in contact with the lower guide 208 to a floating state, it loses its natural frequency f1 and the gain increases. In controlling the mover 101, it is necessary to adjust the control parameters taking into account the natural frequencies f1 and f2 and changes in frequency characteristics when transitioning from a contact state to a floating state.

[0063] 8 is a schematic diagram showing the posture of the mover 101 when it transitions from a state in which it is placed on the lower guide 208 to a levitated state. Ideally, the installation height of the left-side and right-side coils 202L, 202R should be horizontal. However, for example, if the transport device 1 is large, the installation height of the left-side and right-side coils 202L, 202R may not be horizontal due to assembly errors, etc.

[0064] As shown in FIG. 8, a situation in which the mover 101 is levitated when the mounting height of the R-side coil 202R is lower than that of the L-side coil 202L will be described as an example. When levitating the mover 101 by position control, the integrated controller 301 first issues a lift command to lift the mover 101 in the Z direction. Here, as shown in FIG. 8, the distance between the R-side coil 202R and the opposing permanent magnet 103R is shorter than the distance between the L-side coil 202L and the opposing permanent magnet 103L. Therefore, the mover 101 rises while tilting, being lifted from the R side. That is, the mover 101 rises while displacing in the negative Wx direction. At this time, the mover 101 is out of contact with the R-side lower guide 208R but remains in contact with the L-side lower guide 208L as it rises. As the mover 101 rises, the frequency characteristics of the mover 101 gradually approach the floating state shown by the solid line in FIGS. 7A and 7B from the contact state shown by the dashed line in FIGS. 7A and 7B. In other words, the gain increases as the mover 101 rises. Furthermore, as the number of lower guides 208 in contact with the mover 101 decreases, the springiness of the entire lower guide 208 decreases, and the natural frequency f1 of the lower guide 208 decreases. At this time, if the inclination of the mover 101 in the Wx direction is large, the mover 101 continues to rise while remaining in contact with the lower guide 208L. Therefore, the mover 101 approaches the frequency characteristics of the non-contact state while maintaining the natural frequency f1, and oscillates at the natural frequency f1.

[0065] To prevent oscillation of the mover 101 due to the natural vibration at the natural frequency f1, it is necessary to suppress the tilt of the mover 101, i.e., the displacement of the mover 101 in the Wx direction. To suppress this displacement, it is necessary to increase the responsiveness of the mover 101 to the deviation err by setting high control parameters such as the proportional gain and integral gain set in the mover attitude control function 403. However, if the responsiveness of the mover 101 is increased, the responsiveness to the natural frequency f2 also increases, which may cause the mover 101 to oscillate due to the natural vibration at the natural frequency f2.

[0066] In contrast, the transport device 1 according to this embodiment suppresses or prevents the oscillation of the mover 101 due to the natural vibration described above, thereby achieving stable levitation of the mover 101. The transport device 1 according to this embodiment achieves stable levitation of the mover 101 using zero power control. The levitation control of the mover 101 in the transport device 1 according to this embodiment will be described below.

[0067] First, before explaining the levitation control of the mover 101, the equilibrium position of the mover 101 in the transport device 1 will be explained using Fig. 9A to Fig. 9D. Fig. 9A to Fig. 9C are schematic diagrams showing the relationship between the force in the Z direction acting on the mover 101 and the position in the Z direction, and are views of the mover 101 and coil 202 viewed in the X direction. Fig. 9D is a graph showing the relationship between the force in the Z direction acting on the mover 101 and the position in the Z direction.

[0068] 9A is a position (hereinafter referred to as an equilibrium position) where gravity Fg and attractive force Fm acting on mover 101 are balanced. Attractive force Fm is a magnetic attractive force due to permanent magnet 103. When mover 101 is located at equilibrium position P0, the relationship of gravity Fg = attractive force Fm holds.

[0069] 9B is a position where the gap in the Z direction between the permanent magnet 103 and the coil 202 is smaller than that at the equilibrium position P0. When the mover 101 is located at position P1, the relationship is such that gravity Fg<attraction force Fm.

[0070] 9C is a position where the gap between the permanent magnet 103 and the coil 202 is larger than that at the equilibrium position P0. When the mover 101 is located at the position P2, the relationship is such that gravity Fg>attraction force Fm.

[0071] That is, as shown in FIG. 9D, the relationship between the force in the Z direction acting on the mover 101 and the position in the Z direction is such that, while gravity Fg remains constant even when the position in the Z direction represented by the horizontal axis changes, the attractive force Fm is generally proportional to the square of the distance between the permanent magnet 103 and the coil 202. The mover 101 in the conveyance device 1 according to this embodiment operates only in a region where the attractive force Fm is sufficiently proportional. Therefore, the attractive force Fm can be treated as a force with which an approximate linear relationship holds, as indicated by the dashed dotted line in the graph shown in FIG. 9D.

[0072] The mover 101 is stable at the equilibrium position P0, but when it is positioned higher than the equilibrium position P0, it tries to rise further due to the attractive force Fm. Furthermore, when it is positioned lower than the equilibrium position P0, it tries to descend due to the force of gravity Fg. This characteristic of the mover 101 is called a negative spring characteristic because it is the opposite of a normal spring characteristic (hereinafter referred to as a positive spring characteristic). The mover 101 can have negative spring characteristics in the Z direction, Wx direction, and Wy direction. Here, the slope of the attractive force Fm in the graph shown in FIG. 9D is called the negative spring constant or magnetic spring constant Kmag. The magnetic spring constant Kmag can be found from the relationship between the actual levitation height of the mover 101 and the command torque in the Z direction, or can be calculated in advance by magnetic circuit simulation.

[0073] In the Wx direction, as shown in Fig. 9A, the position where the R-side attractive force FmR and the L-side attractive force FmL are balanced is the equilibrium position P0. The R-side attractive force FmR is the magnetic attractive force due to the R-side permanent magnet 103R. The L-side attractive force FmL is the magnetic attractive force due to the L-side permanent magnet 103L. Similarly, in the Wy direction (not shown), the equilibrium position is the position where the attractive forces before and after the origin Oc, which is the center of gravity of the mover 101, are balanced.

[0074] Zero power control is a control method that can be applied only to control directions in which the mover 101 has negative spring characteristics. In this embodiment, when the mover attitude control function 403 outputs positive torque, that is, when the mover 101 is at a position lower than the equilibrium position, the torque control function 605 calculates a manipulated variable d that updates the target position of the mover 101 in a positive direction. On the other hand, when the mover attitude control function 403 outputs negative torque, that is, when the mover 101 is at a position higher than the equilibrium position, the torque control function 605 calculates a manipulated variable d that updates the target position of the mover 101 in a negative direction. In this way, the torque control function 605 causes the mover 101 to track toward the equilibrium position. In this embodiment, zero power control is used in the Z direction, Wx direction, and Wy direction, which are control directions in which the mover 101 has negative spring characteristics.

[0075] Next, a control method for stably levitating the mover 101 using zero power control will be described. Specifically, the flow of transition of the mover 101 from a contact state to a non-contact state using zero power control (hereinafter referred to as a levitation sequence) will be described with reference to Fig. 10 and Fig. 11. For simplicity, the description will focus on the Z direction and Wx direction as control directions using zero power control.

[0076] FIG. 10 is a graph showing the transition of the position of the mover 101 in the Z direction and the position in the Wx direction during the levitation sequence. In FIG. 10, the vertical axis of the upper graph (1) indicates displacement in the Z direction, and the vertical axis of the lower graph (2) indicates displacement in the Wx direction. The horizontal axis of both graphs indicates time. In both graphs, the solid line indicates the actual position and attitude fb of the mover 101, the dashed-dotted line indicates the target value ref2, and the dashed line indicates the applied torque Tq. Z1 is the position command target value ref1 given when performing position control in the Z direction. ZE and WxE are equilibrium positions in the Z direction and Wx direction, respectively, and are positions where the target value ref2 updated by zero power control converges.

[0077] 11A to 11C are schematic diagrams showing the postures of the mover 101 corresponding to sections (a) to (c) on the horizontal axis indicating time in Fig. 10. Here, it is assumed that the mounting height of the R-side coil 202R facing the R-side permanent magnet 103R is lower than the mounting height of the L-side coil 202L facing the L-side permanent magnet 103L, and the magnetic attractive force on the R-side is greater than the magnetic attractive force on the L-side.

[0078] First, it is assumed that the power supply to the transport device 1 is off and the mover 101 is placed on the lower guide 208. At this time, the mover 101 is in the state shown in FIG.

[0079] When the power supply to the transport device 1 is turned on at time 0 and the levitation sequence starts, the integrated controller 301 starts processing the control blocks shown in FIG.

[0080] First, the integrated controller 301 sets Z1 as the position command target value ref1 in the Z direction. Z1 is a value set to determine the direction of the torque required to levitate the mover 101, and is set to a value smaller than the equilibrium position ZE. At this time, the integrated controller 301 sets the position command target values ​​ref1 in the Wx and Wy directions to the positions at time 0 so as to maintain the current attitude. The integrated controller 301 sets the position command target values ​​in a ramp function manner. At this time, the switch 606 outputs 0, and the target value ref2 becomes equal to ref1. In other words, the mover 101 is controlled by position control. In this way, the integrated controller 301 starts position control of the mover 101 in the Z direction, which is the levitation direction in which the mover 101 levitates from the lower guide 208 when the mover 101 is in contact with the lower guide 208.

[0081] By setting Z1 as the Z-direction position command target value ref1 and issuing a position command in the Z direction, fb rises in the Z direction toward Z1, but the mover 101 is subjected to a vertically downward force due to gravity. As a result, a deviation err occurs between fb and the target value ref2. In addition, the mover 101 starts rising from the R side where the magnetic attractive force is stronger. As a result, as shown in FIG. 11B, the mover 101 is out of contact with the R-side lower guide 208R and in contact with the L-side lower guide 208L, resulting in a half-floating posture. At this time, fb in the Wx direction changes in the negative direction, resulting in a deviation err between fb and the target value ref2.

[0082] When the position command is completed and the Z-direction position command target value ref1 reaches Z1, the switch 606 switches the output source and outputs the manipulated variable d as the output of the torque control function 605. As a result, the target value ref2 becomes ref1 + d. As a result, after the position control, the integrated controller 301 starts zero power control of the mover 101 in the Z direction and the Wx direction when the mover 101 is in contact with the lower guide 208L. That is, the integrated controller 301 starts zero power control in the Z direction and the Wx direction after the mover 101 separates from the lower guide 208R, which is one of the lower guides 208L and 208R, due to the position control. Note that the integrated controller 301 can start zero power control in at least one direction among the Z direction, the Wx direction, and the Wy direction.

[0083] Zero power control changes the target value in the direction of the deviation to reduce the applied torque Tq. Therefore, zero power control updates the target value in the positive direction in the Z direction, i.e., in the levitation direction. Zero power control also updates the target value in the positive direction in the Wx direction, i.e., in the direction opposite to the tilt of the mover 101. As the mover 101 rises in the Z direction due to zero power control, the tilt of the mover 101 increases. In addition to the negative change in fb in the Wx direction due to the tilt of the mover 101, zero power control changes the target value in the positive direction, further increasing the deviation err in the Wx direction. The mover attitude control function 403 increases the applied torque Tq as the deviation increases. As the applied torque Tq increases, the tilt of the mover 101 is suppressed, and eventually the deviation err begins to decrease. Here, if zero power control is not enabled, the applied torque Tq will be insufficient because a sufficient deviation err cannot be obtained, and the tilt cannot be suppressed. This may result in oscillation and failure to levitate the mover 101.

[0084] As the mover 101 rises while its tilt is suppressed, it eventually separates from the lower guide 208L and transitions to a levitated state. Zero power control causes the target value ref2 to converge to the equilibrium position, and fb follows suit. At this time, the tilt of the mover 101 approaches the angle formed by the difference in height between the R-side coil 202R and the L-side coil 202L, as shown in FIG. 11C. Eventually, fb reaches the equilibrium position, completing the levitation sequence.

[0085] In this way, after the position control, the integrated controller 301 starts the zero power control on the mover 101 when the mover 101 is in contact with the lower guide 208 , thereby levitating the mover 101 from the lower guide 208 .

[0086] As described above, the conveyance device 1 according to this embodiment starts zero power control in a control direction with negative spring characteristics from a state in which the mover 101 contacts the lower guide 208. As a result, according to this embodiment, oscillation of the mover 101 due to natural vibration is suppressed or prevented, and even a mover 101 that is large and has low rigidity can be levitated stably.

[0087] In this embodiment, Z1, which is small enough to prevent the mover 101 from going into a non-contact state, is given as the target value of the position command, and then the position control is switched to zero power control, thereby starting zero power control when the mover 101 is in a contact state. However, this switching from position control to zero power control may be performed under other conditions. For example, a sensor that detects contact with the mover 101 may be provided on the lower guide 208, and the switching from position control to zero power control may be performed on the condition that the sensor detects that the mover 101 has gone into a non-contact state with one of the lower guides 208.

[0088] Furthermore, in this embodiment, the levitation direction of the mover 101 is the positive Z direction, but this is not limited to this. For example, even when the levitation direction is the negative Z direction, that is, when the levitation sequence is started from a state in which the mover 101 is attracted to the upper guide 207 by magnetic attraction force, a control method for performing zero power control similar to the above can be applied. Furthermore, as long as the control direction is one in which zero power control is applicable, a control method for performing zero power control similar to the above can be applied, and the axis of the levitation direction of the mover 101 is not limited to the Z direction. For example, even in a device in which a mover including a magnetic body sandwiched between coils arranged on the left and right is levitated in the left-right direction, the mover can be stably levitated by performing zero power control using a levitation sequence similar to the above.

[0089] Furthermore, in the present embodiment, the magnetic force acting between the permanent magnet 103 and the coil 202 is used as the levitation force for levitating the mover 101, but the present invention is not limited to this. The mover 101 may be configured to be levitated by the magnetic force acting between the first magnetic force portion of the mover 101 and the second magnetic force portion of the stator 201. In this case, one of the first magnetic force portion and the second magnetic force portion may include the permanent magnet 103, and the other may include the coil 202.

[0090] [Second embodiment] A magnetic levitation device according to a second embodiment of the present invention will be described with reference to Figures 12 to 14. In the second embodiment, a conveyance device will also be described as an example of a magnetic levitation device. Furthermore, components similar to those in the first embodiment will be given the same reference numerals, and descriptions thereof will be omitted or simplified.

[0091] The configuration of the transport device 1 according to this embodiment is similar to the configuration of the transport device 1 according to the first embodiment. The transport device 1 according to this embodiment is characterized in that the condition for starting zero power control is determined based on the magnitude relationship between the spring constant of the lower guide 208 that contacts the mover 101 and the magnetic spring constant.

[0092] First, a control method for the mover 101 executed by the integrated controller 301 in the transport device 1 according to this embodiment will be described with reference to Fig. 12. Fig. 12 is a schematic diagram showing a control block for controlling the position and attitude of the mover 101 in the transport device 1 according to this embodiment. The integrated controller 301 executes control using the control block shown in Fig. 12.

[0093] 12, P is the position and orientation of the mover 101, and has components (X, Y, Z, Wx, Wy, Wz). ref1 is a position command target value that commands the target value of (X, Y, Z, Wx, Wy, Wz). err is the deviation between the position command target value ref1 and the position and orientation P.

[0094] The mover attitude control function 403 calculates the desired applied torque Tq from the magnitude of the deviation err, the change in the deviation err, the integrated value of the deviation err, and the like.

[0095] Based on the applied torque Tq and the position and attitude P, the coil current calculation function 404 calculates the desired coil current I to be applied to the coil 202 in order to apply the applied torque Tq to the mover 101. When the coil current I calculated in this way is applied to the coil 202, the applied torque Tq acts on the mover 101, and the position and attitude P of the mover 101 change again.

[0096] Furthermore, the integrated controller 301 can control the torque applied to the mover 101 by further executing processing using a torque control function 605. The torque control function 605 calculates the manipulated variable d for the target value ref2 from the integrated value of the difference between the applied torque Tq and the command torque Trqref. In this embodiment, the integrated controller 301 can also use the torque control function 605 as a function for zero power control by always setting Tz', Twx', and Twy' out of the components of the command torque Trqref to zero, as in the first embodiment.

[0097] Furthermore, the integrated controller 301 uses a switch 606 as switching means for switching between position control and zero power control as control for the mover 101. In this embodiment, the switch 606 determines the contact state between the mover 101 and the lower guide 208 using the values ​​of the position and orientation P of the mover 101, and compares the magnitude relationship between the spring constant and the magnetic spring constant of the lower guide 208. As a result of the comparison, the switch 606 outputs a value of 0 if the magnetic spring constant is less than or equal to the spring constant of the lower guide 208, and outputs d if the magnetic spring constant is greater than the spring constant of the lower guide 208. The output of the switch 606 is added to a position command target value ref1. As a result, the target values ​​for the position and orientation of the mover 101 are updated from ref1 to ref2.

[0098] 12 controls the position and attitude of the mover 101 by position control when the output of the switch 606 is a value of 0, and controls the position and attitude of the mover 101 by zero power control when the output of the switch 606 is a manipulated variable d. By configuring the control block in this way, it becomes possible to control the position and attitude of the mover 101 to a desired position and attitude.

[0099] 13A to 13D, the relationship between the reaction force and attractive force that the mover 101 receives from the lower guide 208 at each height of the mover 101 in the transport device 1 will be described. Here, it is assumed that the mounting height of the R-side coil 202R facing the R-side permanent magnet 103R is lower than that of the L-side coil 202L facing the L-side permanent magnet 103L, and the magnetic attractive force on the R-side is greater than that on the L-side.

[0100] FIG. 13A is a schematic diagram showing a state in which the mover 101 is placed on the lower guide 208 in an uncontrolled state, such as when the power to the transport device 1 is off. The position of the mover 101 in the Z direction at this time is defined as P1. The distance in the Y direction from the center of the mover 101 to the central axis of the lower guide 208L along the Z direction is defined as +1, and the distance in the Y direction from the center of the mover 101 to the central axis of the lower guide 208R along the Z direction is defined as −1. The reaction force Fr from the lower guide 208 is the sum of the reaction force FrL from the L-side lower guide 208L and the reaction force FrR from the R-side lower guide 208R. In the state shown in FIG. 13A, gravity Fg acting on the mover 101 is balanced by the sum of the reaction force Fr from the lower guide 208 and the attractive force Fm.

[0101] 13B is a schematic diagram showing a state in which the levitation sequence has started and mover 101 is transitioning to a levitated state. The position of mover 101 in the Z direction at this time is defined as P2. The amount of change in the height of the center of gravity of mover 101 in the Z direction when moving from position P1 to position P2 is defined as ΔZ, and the amount of change in the Wx direction is defined as ΔWx. Furthermore, the amount of change in the position of mover 101 in the Z direction on the central axis of lower guide 208R is defined as ΔZR, and the amount of change in the position of mover 101 in the Z direction on the central axis of lower guide 208L is defined as ΔZL. ΔZR and ΔZL can be calculated using the following equations. ΔZR=ΔZ-l*sin(ΔWx) ΔZL=ΔZ+l*sin(ΔWx)

[0102] By issuing a position command in the Z direction, the mover 101 starts to rise from the R side where the magnetic attraction force is stronger. As a result, the mover 101 is out of contact with the R-side lower guide 208R, but is in contact with the L-side lower guide 208L, resulting in a one-sided floating posture. At this time, ΔZ<ΔZR. Furthermore, when the elastic deformation of the lower guide 208L is also taken into consideration, it can be said that ΔZL≦0.

[0103] 13C is a schematic diagram showing a state in which the levitation sequence is completed and the mover 101 has reached the equilibrium position P0 in the Z direction. The mover 101 reaches the equilibrium position P0 via a position P3 in the Z direction (see FIG. 13D) where the mover 101 is out of contact with the lower guides 208R and 208L.

[0104] Here, the relationship between the spring constants of the lower guides 208R and 208L and the magnetic spring constant Kmag at the positions of the mover 101 shown in FIGS. 13A to 13C will be described with reference to FIG. 13D. Here, the spring constants of the lower guides 208R and 208L are respectively Kr. FIG. 13D is a graph showing the relationship between the spring constants of the lower guides 208R and 208L and the magnetic spring constant Kmag. The vertical axis of the graph shown in FIG. 13D represents force, and the horizontal axis represents position in the Z direction. In the graph, the solid line represents the attractive force Fm. The mover 101 in the conveyance device 1 according to this embodiment operates only in a region where a sufficiently proportional relationship is established with respect to the attractive force Fm. Therefore, the attractive force Fm can be treated as a force for which a relationship established by an approximate straight line Fm′ is established, as shown by the dashed-dotted line in the graph shown in FIG. 13D. The slope of the straight line Fm′ represents the magnetic spring constant Kmag. In the graph, the dashed line represents the reaction force Fr that the mover 101 receives from the lower guide 208. The slope of the straight line Fr in the section from position P1 to position P2 is defined as spring constant Kr1, and the slope of the straight line Fr in the section from position P2 to position P3 is defined as spring constant Kr2.

[0105] At position P1, the mover 101 abuts against two points, the lower guide 208L and the lower guide 208R. At this time, the spring constant of the entire lower guide 208 is Kr1=Kr*2.

[0106] When the position of the mover 101 in the Z direction moves from position P1 to position P2, the mover 101 comes into contact with the lower guide 208L at one point. Therefore, the spring constant of the entire lower guide 208 at this time is Kr2 = Kr. At this time, the relationship between the magnetic spring constant Kmag and the spring constant of the entire lower guide 208 is Kmag > Kr2, and negative spring characteristics become dominant. As described in the first embodiment, zero power control is a control method that can be applied only to control directions with negative spring characteristics. Therefore, if the mover 101 is in a position where Kmag > Kr2, zero power control is possible even if the mover 101 is in contact with the lower guide 208.

[0107] Position P3 is a position where the reaction force Fr that mover 101 receives from lower guide 208 becomes zero. That is, position P3 is a position where mover 101 is out of contact with lower guide 208R and lower guide 208L.

[0108] Next, the levitation sequence of the mover 101 in the transport device 1 according to this embodiment will be described with reference to Fig. 14. Fig. 14 is a flowchart showing the levitation sequence of the mover 101 in the transport device 1 according to this embodiment.

[0109] In the initial state when the levitation sequence starts, the mover 101 is placed on the lower guide 208. The spring constant Kr and magnetic spring constant Kmag of the lower guide 208 are prepared in advance through simulation, measurement, etc.

[0110] First, the integrated controller 301 executes step S100 and issues a position command to levitate the mover 101 in the Z direction, which is the levitation direction, by position control. At this time, the integrated controller 301 issues the position command as a ramp function, and the target value is set to be sufficiently smaller than the equilibrium position.

[0111] Next, the integrated controller 301 executes step S101, and compares which is larger at the current position of the mover 101: the magnetic spring constant Kmag or the spring constant of the entire lower guide 208. The spring constant of the entire lower guide 208 varies depending on how many lower guides 208 the mover 101 is in contact with, as described above.

[0112] Here, a method for determining whether the lower guide 208 is in contact with the mover 101 will be described using the state shown in FIG. 13B as an example. In the state shown in FIG. 13B, a position command in the Z direction, which is the levitation direction, is given, so ΔZ≠0. Furthermore, in this state, ΔZR>ΔZ and ΔZL≦0. When these three equations are satisfied, the integrated controller 301 can determine that the mover 101 is in contact with the lower guide 208L. A similar relationship also holds for the lower guide 208R. Therefore, when ΔZ≠0, ΔZL>ΔZ, and ΔZR≦0, the integrated controller 301 can determine that the mover 101 is in contact with the lower guide 208R. The sum of the spring constants of the lower guides 208 in contact with the mover 101 is the spring constant of the entire lower guide 208.

[0113] If it is determined that the magnetic spring constant Kmag is equal to or less than the spring constant of the entire lower guide 208 (step S101, NO), the integrated controller 301 executes step S100 again, and further raises the position of the mover 101 in the Z direction.

[0114] On the other hand, if it is determined that the magnetic spring constant Kmag is greater than the spring constant of the entire lower guide 208 (step S101, YES), the integrated controller 301 executes step S102.

[0115] In step S102, the integrated controller 301 starts zero power control of the mover 101 in the Z direction, Wx direction, and Wy direction. Once the zero power control is started, the mover 101 eventually reaches an equilibrium position. When the mover 101 reaches the equilibrium position, the levitation sequence is completed.

[0116] As described above, the conveyance device 1 according to this embodiment starts zero power control in a control direction with negative spring characteristics from a state in which the mover 101 contacts the lower guide 208. As a result, according to this embodiment, oscillation of the mover 101 due to natural vibration is suppressed or prevented, and even a mover 101 that is large and has low rigidity can be levitated stably.

[0117] Note that, in this embodiment, an example has been described in which the mover 101 is supported in contact with two lower guides 208, but the number of lower guides 208 in contact with the mover 101 is not limited to this. For example, consider a case in which the lower guide 208 is disposed toward the back of the paper in Figures 13A to 13C. In this case, the contact state between the mover 101 and the lower guide 208 can be determined and the spring constant of the entire lower guide 208 can be calculated by using the distance from the center of the mover 101 to the lower guide 208 and the amount of change of the mover 101 in the Z direction and the Wy direction.

[0118] In addition, in this embodiment, the position and posture of the mover 101 are used to determine the number of lower guides 208 in contact with the mover 101, but this is not limiting. For example, a sensor that detects contact with the mover 101 may be provided on the lower guide 208, and the number of lower guides 208 in contact with the mover 101 may be determined based on the output of the sensor.

[0119] Furthermore, the control method of the mover 101 using zero power control according to this embodiment can be applied to cases where the mover 101 is levitated in other levitation directions, such as the negative Z direction, left and right directions, in addition to the positive Z direction, as in the first embodiment.

[0120] [Third embodiment] A magnetic levitation device according to a third embodiment of the present invention will be described with reference to Fig. 15. In this embodiment, a rotary drive device will be described as an example of a magnetic levitation device. Fig. 15 is a schematic diagram showing a rotary drive device 10 according to this embodiment, as seen from diagonally above.

[0121] 15, the rotary drive device 10 according to this embodiment has a rotor 800, which is an example of a mover, and a stator 900. The rotor 800 has a plurality of first permanent magnets 801a and a plurality of second permanent magnets 801b, which are an example of a plurality of magnets, as a permanent magnet group, which is an example of a magnet group. The stator 900 has a plurality of first coils 901a and a plurality of second coils 901b, which are a coil group. The stator 900 also has sensors 911, 912, and 913 for detecting the displacement or attitude of the rotor 800.

[0122] Rotor 800 has a hollow cylindrical shape with a central axis that is, for example, an axis that is aligned in the horizontal direction, which is a direction that intersects the direction of gravity. Rotor 800 is configured to be rotatable in a rotational direction around the central axis that serves as the rotation axis. Note that the shape of rotor 800 is not limited to a hollow cylindrical shape. The shape of rotor 800 may be any shape that allows rotation around a rotation axis that is aligned in a direction that intersects the direction of gravity, and may be another shape, such as a cylindrical shape, depending on the configuration of the device that utilizes the rotation of rotor 800.

[0123] The plurality of first permanent magnets 801a, which are a permanent magnet group, are attached and installed so as to be evenly aligned in a row circumferentially along the direction of rotation on the outer circumferential side surface of rotor 800 on which yoke 802 is installed. The plurality of second permanent magnets 801b, which are also a permanent magnet group, are attached and installed so as to be evenly aligned in a row circumferentially along the direction of rotation on the outer circumferential side surface of rotor 800 on which yoke 802 is installed. For example, the plurality of first permanent magnets 801a are installed so as to be circumferentially aligned on the outer circumferential side surface of one end in the direction along the central axis of rotor 800, and the plurality of second permanent magnets 801b are installed so as to be circumferentially aligned on the outer circumferential side surface of the other end in the direction along the central axis of rotor 800. In this manner, the plurality of first permanent magnets 801a and the plurality of second permanent magnets 801b are arranged in rotor 800.

[0124] The stator 900 is provided with a plurality of first coils 901a and a plurality of second coils 901b located above the rotor 800 in the direction of gravity on the outside of the rotor 800 so as to face the first permanent magnets 801a and the second permanent magnets 801b. The first coils 901a are attached to positions that allow them to face the first permanent magnets 801a of the rotor 800 so as to be evenly aligned in a row in an arc along the direction of rotation. The second coils 901b are attached to positions that allow them to face the second permanent magnets 801b of the rotor 800 so as to be evenly aligned in a row in an arc along the direction of rotation. In this manner, the first coils 901a and the second coils 901b are arranged in the stator 900.

[0125] Thus, the rotor 800 is disposed below the plurality of first coils 901a and the plurality of second coils 901b in the direction of gravity. When a current is applied to the first coil 901a and the second coil 901b by the controller, an electromagnetic force is generated between the first coil 901a and the second coil 901b and the rotor 800, and acts on the rotor 800. This causes levitation control and rotation control of the rotor 800. The rotor 800 is levitated in the direction of gravity by the levitation control, and rotates around the rotation axis by the rotation control. Before levitation, the rotor 800 is placed on and supported by a plurality of guides (not shown).

[0126] As described above, the rotary drive device 10 according to this embodiment has a rotor 800 having a rotation axis that intersects with the direction of gravity, and a stator 900 disposed above the rotor 800 in the direction of gravity, and rotates the rotor 800 while magnetically levitating the rotor 800 in the direction of gravity. When levitating the rotor 800, the controller can execute a control method using zero power control similar to that of the first or second embodiment, thereby enabling the rotor 800 to be levitated. This suppresses or prevents oscillation of the rotor 800, and makes it possible to achieve stable levitation of the rotor 800 even if the rotor 800 is large and has low rigidity.

[0127] In this embodiment, the magnetic force acting between the first and second permanent magnets 801a, 801b and the first and second coils 901a, 901b is used as the levitation force for levitating the rotor 800. However, the present invention is not limited to this. The rotor 800 may be configured to be levitated by the magnetic force acting between the first magnetic force portion of the rotor 800 and the second magnetic force portion of the stator 900. In this case, one of the first magnetic force portion and the second magnetic force portion may include the first and second permanent magnets 801a, 801b, and the other may include the first and second coils 901a, 901b.

[0128] [Other embodiments] The magnetic levitation device according to the present invention can be used as a transport device in a manufacturing system for manufacturing articles such as electronic devices, which transports a workpiece together with a mover to the working area of ​​each process device, such as a machine tool, that performs each work process on the workpiece. The process device that performs the work process may be any device, such as the vapor deposition device described above, or a device that assembles parts onto the workpiece or a device that paints the workpiece. Furthermore, the article to be manufactured is not limited to a specific one, and may be any part. In this way, the magnetic levitation device according to the present invention can be used to transport the workpiece to the working area, and the workpiece transported to the working area can be subjected to the work process to manufacture the article.

[0129] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0130] The disclosure of this embodiment includes the following configurations and methods. (Configuration 1) a mover having a first magnetic force portion; a second magnetic force portion provided at a position facing the first magnetic force portion, and a magnetic force acting between the second magnetic force portion and the first magnetic force portion; a guide portion that supports the mover; a control unit that controls the position and attitude of the mover, one of the first magnetic force unit and the second magnetic force unit includes a coil and the other includes a permanent magnet; the control unit controls the position and attitude of the mover by controlling a current flowing through the coil; The control unit starts position control of the mover in a levitation direction in which the mover levitates from the guide unit when the mover is in contact with the guide unit, and after the position control, starts zero power control of the mover when the mover is in contact with the guide unit, thereby levitating the mover from the guide unit. A magnetic levitation device characterized by: (Configuration 2) The guide portion is plural, The control unit starts the zero power control after the mover is separated from one of the plurality of guide units by the position control. 2. The magnetic levitation device according to claim 1. (Configuration 3) The control unit controls the position and attitude of the mover in a first direction that is the levitation direction, a second direction intersecting the first direction, a third direction intersecting the first and second directions, a fourth direction that is a rotation direction around a first axis along the first direction, a fifth direction that is a rotation direction around a second axis along the second direction, and a sixth direction that is a rotation direction around a third axis along the third direction. 3. The magnetic levitation device according to configuration 1 or 2. (Configuration 4) The first direction is the vertical direction. 4. The magnetic levitation device according to configuration 3. (Configuration 5) The second and third directions are horizontal directions. 5. The magnetic levitation device according to configuration 3 or 4. (Configuration 6) The control unit starts the zero power control in at least one direction among the first direction, the fifth direction, and the sixth direction. 5. The magnetic levitation device according to any one of configurations 3 and 4. (Configuration 7) The mover has a negative spring characteristic in at least one direction among the first direction, the fifth direction, and the sixth direction. 7. The magnetic levitation device according to configuration 6, (Configuration 8) The control unit starts the zero power control when the magnetic spring constant of the mover is larger than the spring constant of the guide unit. 8. The magnetic levitation device according to any one of configurations 1 to 7. (Configuration 9) the first magnetic force portion includes the permanent magnet, The second magnetic force portion includes the coil. 9. The magnetic levitation device according to any one of configurations 1 to 8. (Configuration 10) The movable element is movable in a direction intersecting the floating direction while floating in the floating direction. 10. The magnetic levitation device according to any one of configurations 1 to 9. (Method 1) A method for controlling a magnetic levitation device having a mover having a first magnetic force portion, a second magnetic force portion provided at a position facing the first magnetic force portion and having a magnetic force acting between the mover and the first magnetic force portion, and a guide portion supporting the mover, wherein one of the first magnetic force portion and the second magnetic force portion includes a coil and the other includes a permanent magnet, a control unit controls the position and attitude of the mover by controlling a current flowing through the coil; The control unit starts position control of the mover in a levitation direction in which the mover levitates from the guide unit when the mover is in contact with the guide unit, and after the position control, starts zero power control of the mover when the mover is in contact with the guide unit, thereby levitating the mover from the guide unit. 2. A method for controlling a magnetic levitation device. (Configuration 11) The magnetic levitation device according to any one of the first to tenth aspects, a process device that performs an operation on the workpiece transported by the mover; A manufacturing system comprising: (Configuration 12) the workpiece is a substrate, The process equipment is a film forming equipment that forms a film on the substrate. 12. The manufacturing system according to claim 11. (Method 2) A method for manufacturing an article using the manufacturing system according to configuration 11 or 12, a step of transporting the workpiece by the mover; performing the operation on the workpiece transported by the mover using the process device; A method for manufacturing an article, comprising: [Explanation of symbols]

[0131] 1. Conveyor device 3. Control device 7 Film deposition equipment 10 Rotational drive unit 101 Mover 103 Permanent Magnets 201 Stator 202 Coil 207 Upper guide 208 Lower guide 301 Integrated Controller 800 rotor 801a First permanent magnet 801b Second permanent magnet 900 stator 901a First coil 901b Second coil

Claims

1. a mover having a first magnetic force portion; a second magnetic force portion provided at a position facing the first magnetic force portion, and a magnetic force acting between the second magnetic force portion and the first magnetic force portion; a guide portion that supports the mover; a control unit that controls the position and attitude of the mover, one of the first magnetic force portion and the second magnetic force portion includes a coil and the other includes a permanent magnet; the control unit controls the position and attitude of the mover by controlling a current flowing through the coil; The control unit starts position control of the mover in a levitation direction in which the mover levitates from the guide unit when the mover is in contact with the guide unit, and after the position control, starts zero power control of the mover when the mover is in contact with the guide unit, thereby levitating the mover from the guide unit. A magnetic levitation device characterized by:

2. The guide portion is plural, The control unit starts the zero power control after the mover is separated from one of the plurality of guide units by the position control.

2. The magnetic levitation device according to claim 1.

3. The control unit controls the position and attitude of the mover in a first direction that is the levitation direction, a second direction intersecting the first direction, a third direction intersecting the first and second directions, a fourth direction that is a rotation direction around a first axis along the first direction, a fifth direction that is a rotation direction around a second axis along the second direction, and a sixth direction that is a rotation direction around a third axis along the third direction.

3. The magnetic levitation device according to claim 1 or 2.

4. The first direction is the vertical direction.

4. The magnetic levitation device according to claim 3.

5. The second and third directions are horizontal directions.

4. The magnetic levitation device according to claim 3.

6. The control unit starts the zero power control in at least one direction among the first direction, the fifth direction, and the sixth direction.

4. The magnetic levitation device according to claim 3.

7. The mover has a negative spring characteristic in at least one direction among the first direction, the fifth direction, and the sixth direction.

7. The magnetic levitation device according to claim 6.

8. The control unit starts the zero power control when the magnetic spring constant of the mover is larger than the spring constant of the guide unit.

3. The magnetic levitation device according to claim 1 or 2.

9. the first magnetic force portion includes the permanent magnet, The second magnetic force portion includes the coil.

3. The magnetic levitation device according to claim 1 or 2.

10. The movable element is movable in a direction intersecting the floating direction while floating in the floating direction.

3. The magnetic levitation device according to claim 1 or 2.

11. A method for controlling a magnetic levitation device having a mover having a first magnetic force portion, a second magnetic force portion provided at a position facing the first magnetic force portion and having a magnetic force acting between the mover and the first magnetic force portion, and a guide portion supporting the mover, wherein one of the first magnetic force portion and the second magnetic force portion includes a coil and the other includes a permanent magnet, a control unit controls the position and attitude of the mover by controlling a current flowing through the coil; The control unit starts position control of the mover in a levitation direction in which the mover levitates from the guide unit when the mover is in contact with the guide unit, and after the position control, starts zero power control of the mover when the mover is in contact with the guide unit, thereby levitating the mover from the guide unit.

2. A method for controlling a magnetic levitation device.

12. The magnetic levitation device according to claim 1 or 2; a process device that performs an operation on the workpiece transported by the mover; A manufacturing system comprising:

13. the workpiece is a substrate, The process equipment is a film forming equipment that forms a film on the substrate. The manufacturing system of claim 12 .

14. A method for manufacturing an article using the manufacturing system according to claim 12, a step of transporting the workpiece by the mover; performing the operation on the workpiece transported by the mover using the process device; A method for manufacturing an article, comprising:

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