MOLENAAR, Jacobus, F. (AE Eindhoven, NL-5656, NL)
SAHIN NOMALER, Funda (AE Eindhoven, NL-5656, NL)
VERVOORDELDONK, Michaël, J. (AE Eindhoven, NL-5656, NL)
ANGELIS, Georgo, Z. (AE Eindhoven, NL-5656, NL)
MOLENAAR, Jacobus, F. (AE Eindhoven, NL-5656, NL)
SAHIN NOMALER, Funda (AE Eindhoven, NL-5656, NL)
VERVOORDELDONK, Michaël, J. (AE Eindhoven, NL-5656, NL)
CLAIMS:
1. A magnetic suspension positioning system, comprising: an object (110) physically responsive to an active control of the magnetically suspended object (110) relative to an XYZ reference frame; a magnetic bearing assembly (90-93, 100-103) magnetically suspending the object (110), wherein the magnetic bearing assembly (90-93, 100-103) passively constrains any movement of the magnetically suspended object (110) in a first set of at least one direction of the XYZ reference frame; and at least one magnetic motor (120-122, 130-132) at least partially integrated with the magnetically suspended object (110), wherein each magnetic motor (120-122, 130- 132) is operable to actively control any movement of the magnetically suspended object (110) in a second set of at least one direction of the XYZ reference frame that is different than the first set of at least one direction of the XYZ reference frame.
2. The magnetic suspension positioning system of claim 1, wherein the first set of at least one direction of the XYZ reference frame includes at least one of a linear Z direction, a rotational Rx direction and a rotational Ry direction of the XYZ reference frame; and wherein the second set of at least one direction of the XYZ reference frame includes at least one of a linear X direction, a linear Y direction and a rotational Rz direction of the XYZ reference frame.
3. The magnetic suspension positioning system of claim 1, wherein the magnetic bearing assembly (90-93, 100-103) includes: at least two static magnetic tracks (90, 91, 100, 101), wherein each static magnetic track (90, 91, 100, 101) has a first N-S polarization; and at least one dynamic magnetic track (92, 93, 102, 103) magnetically suspended between the at least two static magnetic tracks (90, 91, 100, 101), wherein each dynamic magnetic track (92, 93, 102, 103) has a second N-S polarization that is opposite to the first N- S polarization.
4. The magnetic suspension positioning system of claim 3, wherein the at least one dynamic magnetic track (92, 93, 102, 103) is integrated with the magnetically suspended object (110) to thereby magnetically suspend the magnetically suspended object (110) between the at least two static magnetic tracks (90, 91, 100, 101).
5. The magnetic suspension positioning system of claim 1, wherein the magnetic bearing assembly (90-93, 100-103) includes at least one passive magnetic (90-93) bearing parallel to the Y linear direction.
6. The magnetic suspension positioning system of claim 1, wherein a first passive magnetic bearing of the at least one passive magnetic bearing includes: at least two static magnetic tracks (90, 91), wherein each static magnetic track (90, 91) has a first N-S polarization; and at least one dynamic magnetic track (92, 93) magnetically suspended between the at least two static magnetic tracks (90, 91), wherein each dynamic magnetic track (92, 93) has a second N-S polarization that is opposite to the first N-S polarization.
7. The magnetic suspension positioning system of claim 6, wherein the at least one dynamic magnetic track (92, 93) is integrated with the magnetically suspended object
(110) to thereby magnetically suspend the magnetically suspended object (110) between the at least two static magnetic tracks (90, 91).
8. The magnetic suspension positioning system of claim 1, wherein a first magnetic motor (120-122) of the at least one magnetic motor (120-122, 130-132) includes: at least two magnetic tracks (121, 122); and a plurality of coils (120) disposed between the at least two magnetic tracks (121, 122).
9. The magnetic suspension positioning system of claim 8, wherein the plurality of coils (120) is static relative to the XYZ reference frame.
10. The magnetic suspension positioning system of claim 8, wherein the plurality of coils (120) is dynamic relative to the XYZ reference frame.
11. The magnetic suspension positioning system of claim 10, wherein the plurality of coils (120) is integrated with the magnetically suspended object (110).
12. The magnetic suspension positioning system of claim 8, wherein the at least two magnetic tracks (121, 122) are static relative to the XYZ reference frame.
13. The magnetic suspension positioning system of claim 8, wherein the at least two magnetic tracks (121, 122) are dynamic relative to the XYZ reference frame.
14. The magnetic suspension positioning system of claim 13, wherein the at least two magnetic tracks (121, 122) are integrated with the magnetically suspended object (110).
15. The magnetic suspension positioning system of claim 8, wherein the plurality of coils (120) are operable for receiving an application of a superimposition of commutation
X currents upon commutation Y currents.
16. The magnetic suspension positioning system of claim 15, further comprising: at least one sensor (140-143) operable to sense at least one position of the magnetically suspended object (110) within the XYZ reference frame.
17. The magnetic suspension positioning system of claim 16, wherein the at least one position includes at least one of an X linear position, a Y linear position and a Rz rotational position.
18. The magnetic suspension positioning system of claim 16, wherein the superimposition of commutation X currents upon commutation Y currents is a function of the at least one position of the magnetically suspended object (110) within the XYZ reference frame as sensed by the at least one sensor (140-143).
19. The magnetic suspension positioning system of claim 1, further comprising: at least one sensor (140-143) operable to sense at least one position of the magnetically suspended object (110) within the XYZ reference frame.
20. The magnetic suspension positioning system of claim 19, wherein the at least one position includes at least one of an X linear position, a Y linear position and a Rz rotational position.
21. The magnetic suspension positioning system of claim 11 , wherein the at least one magnetic motor (120-122, 130-132) is operated as a function of the at least one position of the magnetically suspended object (110) within the XYZ reference frame as sensed by the at least one sensor (140-143).
22. A method for positioning an object (110) physically responsive to an active control of the object (110) relative to an XYZ reference frame, the method comprising: magnetically suspending the object (110); passively constraining any movement of the magnetically suspended object (110) in a first set of at least one direction of the XYZ reference frame; and actively controlling any movement of the magnetically suspended object (110) in a second set of at least one direction of the XYZ reference frame that is different than the first set of at least one direction of the XYZ reference frame.
23. The method of claim 22, wherein the first set of at least one direction of the XYZ reference frame includes at least one of linear Z direction, a rotational Rx direction and a rotational Ry direction of the XYZ reference frame; and wherein the second set of at least one direction of the XYZ reference frame includes at least one of linear X direction, a linear Y direction and a rotational Rz direction of the XYZ reference frame.
24. The method of claim 22, wherein the active control of any movement of the magnetically suspended object (110) in at least one of the linear X direction, the linear Y direction and the rotational Rz direction of the XYZ reference frame further includes: sensing at least one position of the magnetically suspended object (110) within the XYZ reference frame.
25. The method of claim 24, wherein the active control of any movement of the magnetically suspended object (110) in at least one of the linear X direction, the linear Y direction and the rotational Rz direction of the XYZ reference frame includes: superimposing commutation X currents upon commutation Y currents, wherein the superimposition of commutation X currents upon commutation Y currents is a function of the sensing at least one position of the magnetically suspended object (110) within the XYZ reference frame. |
Magnetic suspension positioning system
CROSS-REFERENCE TO RELATED APPLICATION
Cross-reference is hereby made to a related co-pending US patent application serial no. 61/071,346 filed on April 23, 2008, entitled "Linear Hybrid Magnetic Bearing," (ref. Philips invention disclosure no. 678683) the contents of which are herein incorporated by reference.
FIELD OF THE INVENTION
The present invention generally relates to positioning systems. The present invention specifically relates to magnetic based positioning systems.
BACKGROUND OF THE INVENTION
In the high end semiconductor industry, machine positioning stages are utilized to perform various functions. Guiding of these stages must meet strict standards as related to lifetime and dynamic performance as well as vacuum and contamination requirements. Such stage guiding can not be done in a conventional manner, such as, for example, by ball bearing guides in view of the vacuum and contamination requirements and gas bearing guides in view of the difficulty of use in such an environment. However, stages with contact less guides based on magnetic forces have proven to be suitable for guiding such positioning stages. Commonly these types of guides are designed with active control in all six (6) degrees of freedom relative to an XYZ reference frame (i.e., X-Y-Z linear directions and Rx-Ry-Rz rotational directions), but such active control increases the complexity of the system hardware and software.
SUMMARY OF THE INVENTION International Publication Number WO 2007/026270 Al to Angelis et al.
(hereinafter "the Angelis Publication"), which is owned by the assignee of the present invention and the entirety of which is hereby incorporated by reference, teaches various orientations of a multiple of 3-phase and/or multiple of 2-phase forcer within a linear air gap of a magnetic track for facilitating a superimposition of two (2) commutation laws that are
orthogonal to thereby attain independent actuation forces in two (2) orthogonal directions. The present invention is premised on incorporating a magnetic motor, particularly as taught by the Angelis Publication, into a positioning system having a magnetic bearing assembly to attain a passive constraint of one or more degrees of freedom with an active control of the remaining degrees of freedom.
One form of the present invention is a magnetic suspension positioning system comprising an object physically responsive to an active control of the object relative to an XYZ reference frame. The magnetic suspension positioning system further comprises a magnetic bearing assembly and one or more magnetic motors. The magnetic bearing assembly magnetically suspends the object, wherein the magnetic bearing assembly passively constrains any movement of the magnetically suspended object in a first set of at least one direction of the XYZ reference frame (e.g., a linear Z direction, a rotational Rx direction and/or a rotational Ry direction). Each magnetic motor is partially or entirely integrated with the object, wherein each magnetic motor is operable, individually or collectively, to actively control any movement of the magnetically suspended object in a second set of at least one direction of the XYZ reference frame (e.g., a linear X direction, a linear Y direction and/or a rotational Rz direction).
A second form of the present invention is a method for positioning an object physically responsive to an active control of the object relative to an XYZ reference frame. The method comprises (1) magnetically suspending the object, (2) passively constraining any movement of the magnetically suspended object in a first set of at least one direction of the XYZ reference frame (e.g., a linear Z direction, a rotational Rx direction and/or a rotational R Y direction), and (3) actively controlling any movement of the magnetically suspended object in a second set of at least one direction of the XYZ reference frame (e.g., a linear X direction, a linear Y direction and/or a rotational Rz direction).
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing forms and other forms of the present invention as well as various features and advantages of the present invention will become further apparent from the following detailed description of various embodiments of the present invention read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the present invention rather than limiting, the scope of the present invention being defined by the appended claims and equivalents thereof.
Figs. 1 and 2 illustrate a first embodiment of a passive magnetic bearing in accordance with the present invention.
Figs. 3 and 4 illustrate a second embodiment of a passive magnetic bearing in accordance with the present invention. Fig. 5 illustrates one embodiment of a passive magnetic bearing assembly in accordance with the present invention.
Fig. 6 illustrates a first embodiment of a magnetic suspension positioning system in accordance with the present invention.
Fig. 7 illustrates a view of Fig. 6 taken along line I-I shown in Fig 6. Fig. 8 illustrates a view of an exemplary superimposition of orthogonal commutation currents as known in the art;
Fig. 9 illustrates a second embodiment of a magnetic suspension positioning system in accordance with the present invention.
Fig. 10 illustrates a view of Fig. 9 taken along line II-II shown in Fig. 9.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Referring to Fig. 1, a passive magnetic bearing 20 employing a pair of static magnetic tracks 21 and 22, and two (2) dynamic magnetic tracks 23 and 24. Static magnetic tracks 21 and 22 are designed to be held stationary relative to an XYZ reference frame 40 in any manner that prohibits any movement of static magnetic tracks 21 and 22 in the X-Y-Z linear directions and the Rχ-Rγ-Rz rotational directions of XYZ reference frame 40. Dynamic magnetic tracks 23 and 24 are disposed between static magnetic tracks 21 and 22 with an opposite N-S polarization as exemplary shown in FIG. 2 that establishes a magnetic suspension gap 25 between static magnetic track 21 and dynamic magnetic track 23, and establishes a magnetic suspension gap 26 between static magnetic track 22 and dynamic magnetic track 24. As a result, passive magnetic bearing 20 has a positive stiffness in the linear Z direction, a negative stiffness in the X linear direction and a zero or negligible negative stiffness in the Y linear direction. Thus, static magnetic tracks 21 and 22 passively constrain any movement of dynamic magnetic tracks 23 and 24 in the Z linear direction, the Rx rotational direction and the Ry rotational direction of XYZ reference frame 40 while facilitating an active control of any movement of dynamic magnetic tracks 23 and 24 in the X linear direction, the Y linear direction and the Rz rotational direction of XYZ reference frame 40.
Fig. 3 illustrates a passive magnetic bearing 30 employing a pair of static magnetic tracks 31 and 32, and a single dynamic magnetic track 33. Static magnetic tracks 31 and 32 are designed to be held stationary relative to XYZ reference frame 41 in any manner that prohibits any movement of static magnetic tracks 31 and 32 in the X-Y-Z linear directions and the Rχ-Rγ-Rz rotational directions of XYZ reference frame 41. Dynamic magnetic track 33 is disposed between static magnetic tracks 31 and 32 with an opposite N-S polarization as exemplary shown in Fig. 4 that establishes a magnetic suspension gap 34 between static magnetic track 31 and dynamic magnetic track 33, and establishes a magnetic suspension gap 35 between static magnetic track 32 and dynamic magnetic track 33. As a result, passive magnetic bearing 30 has a positive stiffness in the linear Z direction, a negative stiffness in the X linear direction and a zero or negligible negative stiffness in the Y linear direction. Thus, static magnetic tracks 31 and 32 passively constrain any movement of dynamic magnetic track 33 in the Z linear direction, the Rx rotational direction and the Ry rotational direction of XYZ reference frame 41 while facilitating an active control of any movement of dynamic magnetic track 33 in the X linear direction, the Y linear direction and the Rz rotational direction of XYZ reference frame 41.
Passive magnetic bearings of the present invention (e.g., passive magnetic bearing 20 as shown in Fig. 1 and passive magnetic bearing 30 as shown in Fig. 3) serve as a basis for a formation of a magnetic bearing assembly for magnetically suspending an object relative to an XYZ reference frame. For example, as shown in Fig. 5, a passive magnetic bearing 60 and a passive magnetic bearing 70 constitute a magnetic bearing assembly for magnetically suspending an object relative to an XYZ reference frame 80.
Specifically, passive magnetic bearing 60 employs a pair of static magnetic tracks 61 and 62 and four (4) dynamic magnetic tracks (of which dynamic magnetic tracks 63-65 are shown) magnetically suspended between static magnetic tracks 61 and 62.
Likewise, passive magnetic bearing 70 employs a pair of static magnetic tracks 71 and 72 and four (4) dynamic magnetic tracks 73-76 magnetically suspended between static magnetic tracks 71 and 72. The dynamic magnetic tracks of passive magnetic bearings 60 and 70 are integrated with object 50 as shown to magnetically suspend object 50 between static magnetic tracks 61 and 62 and static magnetic tracks 71 and 72. As with the dynamic magnetic tracks of passive magnetic bearing 60 and passive magnetic bearing 70, object 50 experiences a positive stiffness in the linear Z direction, a negative stiffness in the X linear direction and a zero or negligible negative stiffness in the Y linear direction. Thus, the passive magnetic bearing assembly 60,70 passively constrains any movement of object 50 in
the Z linear direction, the Rx rotational direction and the Ry rotational direction of XYZ reference frame 80 while facilitating an active control of any movement of object 50 in the X linear direction, the Y linear direction and the Rz rotational direction of XYZ reference frame 80. A magnetic bearing assembly of the present invention (e.g., the magnetic assembly 60,70 shown in Fig. 5) serve as a basis for a partial or complete integration of one or more magnetic motors into an object magnetically suspended by the passive magnetic bearing assembly for purposes of actively controlling any movement of the object that is not passively constrained by the passive magnetic bearing assembly. For example, as shown in Figs. 6 and 7, a passive magnetic bearing assembly employs one passive magnetic bearing having a pair of static magnetic tracks 90 and 91 magnetically suspending a pair of dynamic magnetic tracks 92 and 93, and another passive magnetic bearing having a pair of static magnetic tracks 100 and 101 magnetically suspending a pair of dynamic magnetic tracks 102 and 103. An object 110 is integrated with dynamic magnetic tracks 92, 93, 102 and 103 as shown in Figs. 6 and 7 to thereby be magnetically suspended by static magnetic tracks 90, 91, 100 and 101 (object 110 is shown as being transparent in Fig. 6 for providing a better view therein). As a result, the magnetic bearing assembly passively constrains any movement of object 110 in the Z linear direction, the Rx rotational direction and the Ry rotational direction of an applicable XYZ reference frame.
A magnetic motor as taught by the Angelis Publication employs static coils
120 extending through a channel 111 of object 110, and a pair of dynamic magnetic tracks
121 and 121 extending through respective top and bottom side walls of object 100 into channel 111. Likewise, another magnetic motor as taught by the Angelis Publication employs static coils 130 extending through channel 111 of object 110, and a pair of dynamic magnetic tracks 131 and 132 extending through respective top and bottom side walls of object 100 into channel 111. As result, the magnetic motors can be actuated to actively control any movement of object 110 in the X linear direction, the Y linear direction and the Rz rotational direction of the applicable XYZ reference frame. In particular, as taught by the Angelis Publication, an analogous application of a superimposition of commutation current coils Iχi- 1x3 on orthogonal commutation current coils I Y1 -I Y3 as shown in Fig. 8 to coils 120 and 130 will provide for an active control of any movement of object 110 in the X linear direction and the Y linear direction of the applicable XYZ reference frame. Conversely, a differential application of a superimposition of commutation current coils Iχi-Iχ 3 on orthogonal
commutation current coils I Y1 -I Y3 as shown in Fig. 8 to coils 120 and 130 will provide for an active control of any movement of object 110 in the Rz rotational direction of the applicable XYZ reference frame.
Such active control is dictated by a chosen control scheme that can utilize a pair of sensors 140 and 141 (e.g., inductive or capacitive sensors) for sensing an X linear position and a Rz rotational position of object 110 based on a reference surface of object 110. Additionally, to sense a Y linear position of object 110, the chosen control scheme can utilize an optical linear measurement involving a static sensor head 142 that slides along a sensor scale 143 integrated onto object 110 as object 110 is moved in the Y linear direction. By further example, as shown in Figs. 9 and 10, a passive magnetic bearing assembly employs one passive magnetic bearing having a pair of static magnetic tracks 150 and 151 magnetically suspending a pair of dynamic magnetic tracks 152 and 153, and another passive magnetic bearing having a pair of static magnetic tracks 160 and 161 magnetically suspending a pair of dynamic magnetic tracks 162 and 163. An object 170 is integrated with dynamic magnetic tracks 152, 153, 162 and 163 as shown in Figs. 9 and 10 to thereby be magnetically suspended by static magnetic tracks 150, 151, 160 and 161. As a result, the passive magnetic bearing assembly passively constrains any movement of object 170 in the Z linear direction, the Rx rotational direction and the R Y rotational direction of an applicable XYZ reference frame. A magnetic motor as taught by the Angelis Publication employs a dynamic coils 180 integrated within the body of object 170, and a pair of dynamic magnetic tracks 181 and 182 extending through respective channels 171 and 172 of object 170. Likewise, another magnetic motor as taught by the Angelis Publication employs a dynamic coils 190 integrated within the body of object 170, and a pair of static magnetic tracks 192 and 193 extending through respective channels 173 and 174 of object 170. As result, the magnetic motors can be actuated to actively control any movement of object 170 in the X linear direction, the Y linear direction and the Rz rotational direction of the applicable XYZ reference frame. In particular, as taught by the Angelis Publication, an analogous application of a superimposition of commutation current coils Iχi-Iχ 3 on orthogonal commutation current coils I Y1 -I Y3 as shown in FIG. 8 to coils 180 and 190 will provide for an active control of any movement of object 170 in the X linear direction and the Y linear direction of the applicable XYZ reference frame. Conversely, a differential application of the superimposition of commutation current coils Iχi-Iχ3 on orthogonal commutation current coils I Y1 -I Y3 as shown
in FIG. 8 to coils 180 and 190 will provide for an active control of any movement of object 170 in the Rz rotational direction of the applicable XYZ reference frame.
Such active control is dictated by a chosen control scheme that can utilize a pair of sensors 200 and 201 (e.g., inductive or capacitive sensors) for sensing an X linear position and a Rz rotational position of object 170 based on a reference surface of object 170. Additionally, to sense a Y linear position of object 170, the chosen control scheme can utilize linear measurement involving a static sensor head 202 that slides along a sensor scale 203 integrated onto object 170 as object 170 is moved in the Y linear direction.
Referring to Figs. 1-10, those having ordinary skill in the art will appreciate numerous advantages of the present invention including, but not limited to, providing a magnetic suspension positioning system that addresses the drawbacks of previous positioning systems. Furthermore, those having ordinary skill in the art will appreciate how to apply the inventive principles of the present invention to magnetic suspension positioning systems more or less complex than the systems and various components thereof illustrated in Figs. 1- 10. For example, (1) magnetic tracks of the passive magnetic bearings may include one or more magnets and/or one or more magnetic components, (2) static magnetic track(s) of the passive magnetic bearings may employ magnet(s) and/or magnetic components with the same or opposing N-S polarization of the dynamic magnetic track(s) in a manner that passively constrains the dynamic magnetic track(s) in the X linear direction and/or the Rz rotational direction of an applicable XYZ reference frame, (3) the static component of the magnetic motor(s) may be exterior to the object, and (4) steel may be added to channel, direct and/or improve magnetic fields generated by the magnetic tracks.
Still referring to Figs. 1-10, those having ordinary skill in the art will appreciate a magnetic suspension positioning system of the present invention can be utilized in numerous applications, such as, for example, in semiconductor manufacturing applications (e.g., ASML, LAK-Tencor, AMAT, NXP), sample/substrate positioning in reactive or aggressive applications, high acceleration/velocity applications, vacuum applications, production applications, medial applications (e.g., shutter blades in X-ray devices) and consumer electronic applications (e.g., CD/DVD/Blu-Ray drive systems). Irrespective of the actual application, a magnetic suspension positioning system of the present invention will be associated with an XYZ reference frame within the environment of the application. Thus, for purposes of the present invention, the term "static" as used herein is descriptive of a component of a magnetic suspension positioning system that is stationary relative to the XYZ
reference frame, and the term "dynamic" as used herein is descriptive of a component of a magnetic suspension positioning system that is movable relative to the XYZ reference frame.
Additionally, in practice, the actual structural configuration and relative dimensioning of each component of a magnetic suspension positioning system of the present invention is dependent upon the specifics of an explicit application of the system. Thus, the present invention does not contemplate any particular type of best structural configuration and relative dimensioning of each component of a magnetic suspension positioning system of the present invention among the numerous potential applications. Nonetheless, it has been discovered that a realistic geometry of 8mm x 4mm x 30mm for magnets used in the magnetic tracks and provide a stiffness of 2.2* 10 4 N/Mm that provides sufficient linearity in the Y linear direction and sufficiently low crosstalk of the Y-stiffness of the magnets moving in the X linear direction.
While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.
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