Adjustable magnetic counterbalance

Abstract

To provide an adjustable magnetic counterbalance assembly in which counterbalance force of an adjustable magnetic counterbalance is adjustable.SOLUTION: An adjustable magnetic counterbalance assembly includes at least one ferromagnetic tube; a magnet disposed in the at least one ferromagnetic tube and configured to be axially movable and wherein the magnet is configured to be rotationally movable relative to the respective at least one ferromagnetic tube; wherein the counterbalance force is configured to be adjustable by adjusting the rotational position between the magnet and a respective ferromagnetic tube to change the polar alignment of the magnet. Alternatively, the adjustable magnetic counterbalance assembly changes the counterbalance force based on the relative alignment of the poles of one magnet to an adjacent one.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of the prior filing date of U.S. Provisional Patent Application No. 62 / 836,825, filed April 22, 2019, the disclosure of which is incorporated herein by reference. [Background technology]

[0002] Linear motion systems are used to generate precise linear motion along at least one axis of direction. Applications of linear motion systems include any application in which linear motion is considered desirable. In a typical linear motion system, a moving carriage can be driven (moved back and forth) using a variety of motors. These can include, for example, piezoelectric actuators, linear motors, rotary motors and screws, rotary motors and belts, and rotary motors and racks and pinions. Generally, linear motion systems with one degree of freedom (DOF) include a stage featuring a stationary base and a moving carriage or table. Linear motion stages can be combined to form multi-axis linear motion systems with more than one DOF. For example, a first linear motion stage can provide motion along the x-axis, while a second linear motion stage can provide motion along the y-axis, which is perpendicular to the x-axis, to form a dual-axis linear motion system. Examples of linear motion systems can be found in U.S. Pat. Nos. 10,367,436 and 10,374,530, the disclosures of which are incorporated herein by reference. The linear motion stage can be oriented vertically. An embodiment of the present disclosure uses a magnetic counter balance to counterbalance gravity on the linear stage (when oriented vertically). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 10,367,436 [Patent Document 2] U.S. Patent No. 10,374,530 Summary of the Invention

[0004] Various embodiments of the present disclosure are described herein, by way of example, in conjunction with the following figures, in which like reference characters, including those incremented by multiples of 10, may designate the same or similar elements: [Brief description of the drawings]

[0005] [Figure 1] FIG. 2 is a top view of a stage having an adjustable magnetic counterweight assembly according to an embodiment of the present invention. [Figure 2A] FIG. 2 shows possible positions of magnets within the stage of FIG. 1. [Figure 2B] FIG. 2 shows possible positions of magnets within the stage of FIG. 1. [Figure 2C] FIG. 2 shows possible positions of magnets within the stage of FIG. 1. [Diagram 3] FIG. 2 is a perspective view of a stage having an adjustable magnetic counterweight assembly according to an embodiment of the present invention. [Figure 4] FIG. 1 is a perspective view of a conventional miniature linear stage having a non-adjustable magnetic counterweight assembly. [Diagram 5] FIG. 2 is a perspective view of an adjustable magnetic counterweight assembly according to an embodiment of the present invention. [Figure 6A] FIG. 5 is a diagram showing the position of magnets in the stage of FIG. 4. [Figure 6B] 6A-6C show possible positions of magnets in the adjustable magnetic counterweight assembly of FIG. 5. [Figure 6C] 6A-6C show possible positions of magnets in the adjustable magnetic counterweight assembly of FIG. 5. [Figure 7] FIG. 1 is a perspective view of a miniature linear stage having an adjustable magnetic counterweight assembly in accordance with an embodiment of the present invention. [Figure 8] FIG. 8 is a perspective view of the stage of FIG. 7 with the brackets transparent for illustrative purposes. [Figure 9] FIG. 1 is a perspective view of a miniature linear stage having an adjustable magnetic counterweight assembly in accordance with an embodiment of the present invention. [Figure 10A] 10A-B show travel positions of an adjustable magnetic counterweight assembly of the stage of FIG. 9 in accordance with an embodiment of the present invention. [Figure 10B] 10A-B show travel positions of an adjustable magnetic counterweight assembly of the stage of FIG. 9 in accordance with an embodiment of the present invention. [Figure 11] FIG. 13 is a perspective view of an adjustable magnetic counterweight assembly according to another embodiment. [Figure 12] FIG. 13 is a perspective view of a stage having an adjustable magnetic counterbalance assembly according to another embodiment. [Figures 13A-13C] 13A-13C show possible positions of magnets within the adjustable magnetic counterweight assembly of FIG. 12. [Figure 14] FIG. 13 is a perspective view of a stage having an adjustable magnetic counterbalance assembly according to another embodiment. [Figure 15] FIG. 13 is a perspective view of a stage having an adjustable magnetic counterbalance assembly according to another embodiment. [Figure 16] FIG. 13 is a perspective view of a stage having an adjustable magnetic counterbalance assembly according to another embodiment. [Figures 17A-17C] 17A-17C show possible positions of magnets in the adjustable magnetic counterweight assembly of FIG. 16. [Figure 18] FIG. 13 is a perspective view of a stage having an adjustable magnetic counterbalance assembly according to another embodiment. [Figures 19A-19C] 19A-19C show possible positions of magnets in the adjustable magnetic counterweight assembly of FIG. 18. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] In a magnetic counterbalance, a cylindrical magnet polarized N->S across its diameter (as opposed to along its axis) is positioned so that it can move within a ferromagnetic steel tube along a linear axis at various positions. The magnet is attracted to the tube and if it were only concentrically constrained it would retract itself completely into the tube and center itself within the tube, thereby equalizing the force in all directions. By centering and constraining the tube and magnet with a linear axis, a counterbalance can be achieved with a nearly constant linear force. This force is consistent when the magnet is engaged within a steel tube that is long enough that the magnet does not get too close to the end of the tube, since the steel tube only affects the magnetic field a short distance away. Besides magnet size and strength, the amount of counterbalance force is controlled by adjusting the clearance (gap) between the magnet and the tube and the wall thickness of the steel tube. When a system is designed for a user, the user identifies their desired payload and the size of the counterbalance force is designed accordingly.

[0007] Factors that affect the consistency of the counterweight force over the length of travel are the concentricity of the magnet with respect to the steel tube, the magnet charge consistency over the length of the magnet, the magnet size variation over the length of the magnet, and the steel tube size variation over the length of the axial travel.

[0008] The factors that affect the design's stage-to-stage counterweight force variation (manufacturing build consistency) are primarily component variations: magnet-to-magnet charge variation, magnet-to-magnet size variation, tube-to-tube inside diameter (ID) variation, tube-to-tube wall thickness variation, and assembly variation. The embodiments presented herein are intended to allow adjustment for these typical build variations.

[0009] Other obvious benefits include cost savings and inventory minimization. With a wide range of counterweight adjustments, it is also possible to eliminate machining of the tube ID to save costs. It is also possible to reduce the amount of tube stocked to accommodate the full range of counterweight values.

[0010] When the counterbalance is perfectly sized to have a perfectly consistent force over the length of travel, the payload will levitate vertically in any position without any power. When it is not perfectly sized, the system needs to apply power to keep the payload in a fixed position. The power required to hold the system in a fixed position results in heat being introduced into the system, which is undesirable for a high precision instrument.

[0011] In designing a system for a user, it is also necessary to consider what will happen when a power outage occurs. In some cases, the counterweight needs to be sized so that the payload will move upwards to a safe position, and in other cases, the counterweight needs to be sized so that the payload will move downwards to a safe position. The sizing of the counterweight force needs to take into account any errors in build consistency over the length of the run, as well as any errors in force consistency, to ensure that the user's payload will move to a safe position in a power outage situation. This means that some unwanted power and heat will always need to be introduced into the system.

[0012] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure include single or multi-magnet adjustable counterweights for linear motion systems.

[0013] The use of an adjustable counterweight can eliminate more than 50% of the mismatch and therefore also eliminate more than 50% of the unwanted power / heat.

[0014] In some cases, users will have a large number of devices that they will be attaching to their stage, which will cause variations to the overall payload. In the past, this has been addressed by using blocks of weights that users can add and remove from the system whenever they change their device. This approach means that the system needs to be tuned for the largest possible mass and sized for the largest counterweight force. When tuned for the largest mass and sized for the largest counterweight, the performance attributes of the stage (acceleration, deceleration, settling time) are reduced. The use of an adjustable counterweight with an established fixed position can allow the user to make adjustments and thus utilize the ideal tuning parameters for each desired configuration.

[0015] An embodiment of the present disclosure includes an adjustable counterweight magnet where the counterweight force varies based on the relative alignment of the poles of one magnet with respect to its neighbor. This is accomplished by changing the relative rotation or distance between two adjacent magnets. Alternatively, increasing the counterweight force can be achieved with a magnet in a single slotted ferromagnetic tube, and the relative rotational position of the magnet and tube is adjustable. In this alternative embodiment, the counterweight force can be adjusted by rotation of the magnet's magnetic poles relative to slots (or other shaped cutouts) in the ferromagnetic tube. Multiple parallel tubes or magnets are not required with this embodiment.

[0016] 1, the DOF stage 10 includes a counterweight magnet assembly 11 that considers the orientation of three magnets 14A, 14B, 14C supported by a bracket 12 relative to counterweight force variations. This stage was used for testing. The results are in Table 1 below.

[0017] 2A, the magnet orientation is shown to show three magnets 14A, 14B, 14C with their poles oriented to attract each other. This assembly approach has typically resulted in the most consistent counterweight force across multiple stages and batches of material. This is the intended starting point for the magnet orientation before any adjustments.

[0018] Referring to FIG. 2B, the central magnet 14B is rotated 90 degrees to increase the counterweight force.

[0019] Referring to FIG. 2C, the central magnet 14B is rotated 180 degrees to increase the counterweight force.

[0020] Using the same magnets and ferromagnetic steel tubes, once the DOF stage was assembled, adjustments were made to determine the total counterweight force as well as linearity over the entire range of travel. (Table 1) TIFF2025029609000002.tif26141

[0021] This demonstrates that the counterweight force could be increased by 50% without any adverse effect on consistency over the entire range of travel.

[0022] This principle can be applied to counterweight designs that use more than one magnet when the magnets are so close to each other that their magnetic fields interact. The principle is that when the magnetic poles oppose each other (bucking), the magnetic field is projected farther outward so that more of the outer magnets of the counterweight tube can affect the total counterweight force.

[0023] 3, the DOF stage 20 is shown with a mounting base 26 and a moving table 28 on which a user payload is assembled. The DOF stage 20 further includes a counterweight magnet assembly 21 including a counterweight bracket 22 attached to the mounting base with three magnets 24A, 24B, 24C that allow adjustment of a central magnet 24B. Each of the magnets 24A, 24B, and 24C is disposed in a ferromagnetic steel tube 25A, 25B, 25C inserted in the moving table 28, each of the magnets 24A, 24B, and 24C being axially movable with respect to their respective steel tubes. In this embodiment, the central magnet 24B can be rotated to adjust the relative alignment of the poles of the central magnet 24B with the adjacent magnets 24A, 24C. The counterweight bracket 22 includes a manually adjustable rotation adjustment mechanism, such as a screw assembly 29A, that is used to rotate the central magnet 24B within the tube 25B. Screws 29B, 29C or other locking mechanisms are used to lock the ferromagnetic tubes 25A, 25B, 25C in place relative to the moving table 28. If this is to be used on a stage where the user wants to dynamically adjust it for different uses, markings (not shown) are applied to allow the user to iteratively repeat their adjustments.

[0024] 4, a conventional miniature linear stage 30 is shown configured for actuation in a vertical orientation. Stage 30 is shown having a mounting base 36 and a translation table 38. Stage 30 further includes a counterweight magnet assembly 31 including a counterweight bracket 32 ​​attached to mounting base 36 supporting a single magnet 34 disposed on a single ferromagnetic tube 35 mounted to a tube mount bracket 37 attached to translation table 38. The tube 35 is movable axially relative to the magnet 34 as the moving table 38 moves relative to the mounting base 36. The magnet 34 is movable axially relative to the tube 35 as the moving table 38 moves relative to the mounting base 36. In this single magnet counterweight embodiment, the polar orientation of the magnet 34 (polarized N→>S across the diameter) cannot be changed with respect to another magnet to affect the adjustability, therefore another concept is required to achieve the adjustability. In this embodiment, the variables used to control the counterweight force are typically the magnet gap and the wall thickness of the tube.

[0025] Referring to Figure 5, there is shown a single magnet counterweight assembly 41 in which the relative orientation of the magnets is adjustable in accordance with an embodiment of the present invention. As shown in Figure 5, a tube 45 has a pair of diametrically opposed longitudinal slots 43A, 43B (only 43A is shown in Figure 5) and material bonds 45A, 45B at either end of the tube 45. The tube 45 is rotatable relative to the magnet 44 such that the pole position of the magnet 44 is adjustable relative to the slots 43A, 43B of the tube 45, for example, by manually adjusting the rotational position of the tube 45 or the magnet 44 relative to one another.

[0026] Referring to Figure 6A, there is shown a conventional mounting approach for the magnet mounts for the stage of Figure 4. The magnets 34 are always oriented orthogonally (with respect to the polarization direction) on the stage so that there is a consistent orientation for all stages built.

[0027] 6B and 6C, two different adjusted orientations for tube 45 relative to the stage of FIG. 5 are shown.

[0028] FIG. 6B shows the poles of magnet 44 facing the metal of tube 45 (solid slot absent portion), which is the orientation for the lowest counterweight force.

[0029] FIG. 6C shows the pole of magnet 44 facing slot 43, which is the orientation for highest counterweight force.

[0030] The positions of slots 43A, 43B in tube 45 are shown in Figures 6B and 6C and are oriented 90 degrees away from each other. The counterweight force varies throughout the 90 degree range of tube 45 rotation.

[0031] 7, there is shown an adjustable single magnet counterweight assembly 41 mounted to a stage 40. Stage 40 is shown having a mounting base 46 and a moving table 48. Stage 40 further includes a counterweight magnet assembly 41 that includes a counterweight bracket 42 mounted to mounting base 46 having a single magnet 44 disposed in a single ferromagnetic tube 45 mounted to a tube mount bracket 47 that is attached to the moving table 48. Tube 45 has a pair of diametrically opposed longitudinal slots 43A, 43B.

[0032] 8, stage 40 is shown with tube mount bracket 47 illustrated as transparent to clarify that material bonds 45A at the ends of tube 45 are used for structural integrity that allows tube mount bracket 47 to rigidly hold tube 45.

[0033] 9, there is shown a miniature linear stage 50 with an adjustable single magnet counterweight assembly 51 as discussed and tested above. Using a 90 degree rotation of the tube 55, an approximately 300% variation in counterweight force was achieved, moving from 1 kg to 3 kg force. The force was gradually changed throughout the rotation.

[0034] The material bonds 55A, 55B at the ends of the tube 55 do affect the linearity over the travel range of the magnet 54. For large stages with 1 kg or 3 kg counterweights (tested above), linearity is not as important as it is on a DOF stage that must accommodate a .25 kg payload. If the design can accommodate that the ends of the magnet always remain in the central region of the tube's travel, the bonds are not an issue. If the magnet needs to travel close to the end of the tube and linearity is important, the material bonds on the magnet side of the tube need to be removed.

[0035] Referring to FIG. 10A, magnet 54 is shown at position A, which is a constant force region of progression. At position B, shown in FIG. 10B, material bond 55A begins to close and the force is no longer constant.

[0036] Referring to Figure 11, there is shown an adjustable single magnet counterbalance assembly 61 having a bracket 62, a magnet 64, and a counterbalance tube 65 with a material bond 65B at one end and the material bond removed from the opposite end. In this embodiment, the force remains constant much closer to the end of the tube. In this embodiment, there is a non-ferrous collar 70 which helps to retain the mechanical integrity that is lost when the material bond is removed from the tube 65.

[0037] Alternative arrangements may be used to affect the adjustment function of the counterweight, such as multiple slots, all of which must be symmetrical about 180 degrees in phase; both the slots and material can be of different widths; and the length of the material bond can also be a factor in travel length and linearity.

[0038] This principle of a single magnet adjustable counterweight can also be applied to any multi-magnet counterweight.

[0039] Although the embodiment of Figures 1-3 is depicted as rotating a single magnet relative to two outer magnets, it is contemplated that other means of adjusting the counterweight magnetic force may be used. For example, moving one or more magnets closer or farther apart may also be used to adjust the magnetic force.

[0040] Referring to Figures 12-19C, an alternative embodiment is shown for a linear motion stage that is movable relative to a respective base having an adjustable magnetic counterweight having at least two magnets and at least one ferromagnetic tube for changing the relative rotation or distance between two adjacent magnets.

[0041] With reference to Figure 12, an embodiment is shown having a stage 78 supporting a pair of magnets 74A, 74B and a base 76 having a pair of ferromagnetic tubes 75A, 75B disposed therein. Counterweight force adjustment is performed by rotating one of the magnets 74A, 74B which can then be fixed in place. In this embodiment, the tubes 75A, 75B are fixed and not rotated. With reference to Figures 13A-13C, the possible magnet orientations are shown by the position in Figure 13A with the minimum counterweight force, Figure 13B shows the increased counterweight force with one magnet rotated 90 degrees, and Figure 13C shows the maximum force with one magnet rotated 180 degrees.

[0042] Referring to Figure 14, this embodiment is the same as the embodiment of Figure 12 except that only one ferromagnetic tube 85 is used. Either magnet 84A, 84B can be rotated to achieve the same force adjustment function as Figure 13.

[0043] Referring to FIG. 15, this embodiment, which is similar to that of FIG. 3, includes three ferromagnetic tubes 95A, 95B, and 95C, and three magnets 94A, 94B, and 94C, with a central magnet 94B being rotatably adjustable.

[0044] With reference to FIG. 16, this embodiment includes one ferromagnetic tube 105 and two magnets 104A, 104B, one 104B being, for example, non-cylindrical and one 104A being cylindrical, with the cylindrical magnet 104A being disposed in the ferromagnetic tube 105 within a base 106. Rotating the cylindrical magnet 104A increases the attractive force. In this embodiment, the magnets 104A, 104B are aligned within a stage 108 and then fixed in place. With reference to FIG. 17A-17C, the possible magnet orientations are shown by the position in FIG. 17A with the minimum counterweight force, FIG. 17B shows the increased counterweight force with one magnet rotated 90 degrees, and FIG. 17C shows the maximum force with one magnet rotated 180 degrees.

[0045] 18, this embodiment includes one ferromagnetic tube 115 and two magnets 114A, 114B, one of which is, for example, non-cylindrical 114B, while 114A is cylindrical, the cylindrical magnet 114A is disposed in the ferromagnetic tube 115 disposed in a base 116. The non-cylindrical magnet 114B is supported by an adjustment bracket 121 attached to a stage 118 with an adjustment mechanism, such as a screw disposed in an elongated slot. Adjusting the distance between the two magnets 114A, 114B adjusts the counterweight force. Reducing the distance between the magnets 114A, 114B increases the attractive force. Rotating the ferromagnetic tube 115 does nothing. In this embodiment, the magnets 114A, 114B are aligned before assembly and then glued in place. 19A-19C, possible magnet positions are shown by the position in FIG. 19A with the magnets furthest apart having the smallest counterweight force, FIG. 19B shows increasing counterweight force with increasing distance between the magnets, and FIG. 19C shows maximum force with the magnets at the smallest distance between them.

[0046] The ferromagnetic tubes disclosed herein may be cylindrical or non-cylindrical. A non-cylindrical tube may have, for example, a square cross section. The rotation of a square magnet in a non-cylindrical tube with a square cross section is believed to be limited to 0, 90, and 180 degrees.

[0047] Disclosed embodiments of the present invention include manually adjusting the magnetic counterbalance prior to use and then securing the magnet with, for example, adhesive or a clamp. Disclosed embodiments of the present invention also include adjusting the magnetic counterbalance after assembly using an adjustment mechanism such as that shown in FIG.

[0048] Features of the disclosed embodiments can be combined, rearranged, omitted, etc., within the scope of the present invention to produce additional embodiments. Furthermore, certain features may sometimes be used to advantage without the corresponding use of other features.

[0049] Numerous alternatives, modifications, and variations are made possible by the disclosure of the present invention. While particular embodiments have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. Accordingly, the applicant intends to embrace all such alternatives, modifications, equivalents, and variations that are within the spirit and scope of the present invention.

[0050] [Embodiment] (1) An adjustable magnetic counterbalance assembly, the counterbalance force of which is adjustable, comprising: A ferromagnetic tube; a first magnet disposed within the ferromagnetic tube and configured to be axially movable relative to the ferromagnetic tube; Including, At least one of the first and second magnets is configured to be movable relative to the other magnet; The counterweight force is adjustable by adjusting the positions of the magnets relative to each other. 1. An adjustable magnetic counterbalance assembly comprising: (2) 2. The adjustable magnetic counterweight assembly of embodiment 1, wherein at least one of the magnets is cylindrical. (3) 2. The adjustable magnetic counterweight assembly of embodiment 1, wherein at least one of the magnets is configured to rotate relative to the other magnet such that the polar alignment of the magnets can be changed. (4) 2. The adjustable magnetic balance weight assembly of embodiment 1, wherein the ferromagnetic tube includes a first ferromagnetic tube, and the second magnet is disposed within a second ferromagnetic tube positioned parallel to the first ferromagnetic tube. (5) 2. The adjustable magnetic counterweight assembly of embodiment 1, wherein the first and second magnets are coupled to a first component of a linear motion system. (6) 6. The adjustable magnetic counterweight assembly of embodiment 5, wherein the ferromagnetic tube is coupled to a second component of a linear motion system that moves relative to the first component. (7) 2. The adjustable magnetic counterweight assembly of embodiment 1, wherein at least one of the magnets is non-cylindrical. (8) 2. The adjustable magnetic counterweight assembly of embodiment 1, wherein at least one of the magnets is configured to move closer or farther from the other magnet. (9) 2. The adjustable magnetic counterweight assembly of embodiment 1, further comprising a third magnet disposed within a third ferromagnetic tube, the third magnet being disposed between the first and second magnets and configured to rotate relative to the first and second magnets. (10) 1. An adjustable magnetic counterweight assembly comprising: a ferromagnetic tube including at least one perforation; a magnet disposed within the ferromagnetic tube and configured to be movable axially and rotationally relative to the ferromagnetic tube; Including, the magnetic counterbalance assembly is configured such that adjusting a rotational position between the magnet and the ferromagnetic tube changes the polarity alignment of the magnet, thereby changing the magnetic counterbalance force. 1. An adjustable magnetic counterbalance assembly comprising: (11) 11. The adjustable magnetic counterweight assembly of embodiment 10, wherein the magnet is cylindrical. (12) 11. The adjustable magnetic counterweight assembly of claim 10, wherein the rotational position is adjusted by rotating the magnet. (13) 11. The adjustable magnetic counterweight assembly of embodiment 10, wherein the rotational position is adjusted by rotating the ferromagnetic tube. (14) 11. The adjustable magnetic counterweight assembly of embodiment 10, wherein the magnet is coupled to a first component of a linear motion system. (15) 15. The adjustable magnetic counterweight assembly of embodiment 14, wherein the ferromagnetic tube is coupled to a second component of a linear motion system that moves relative to the first component. (16) 11. The adjustable magnetic counterweight assembly of embodiment 10, wherein the ferromagnetic tube is disposed on a moving table of a linear motion system. (17) 11. The adjustable magnetic counterweight assembly of claim 10, wherein the perforations include slots in the ferromagnetic tube. (18) 11. The adjustable magnetic counterweight assembly of claim 10, wherein the perforations include a pair of slots in the ferromagnetic tube. (19) 1. A method for adjusting a counterbalance force in an adjustable magnetic counterbalance assembly, comprising: changing a rotational position of the magnet relative to a ferromagnetic tube in which the magnet is disposed to change a polarity alignment of the magnet relative to the ferromagnetic tube; The ferromagnetic tube has at least one perforation. A method comprising: (20) 1. A method for adjusting a counterbalance force in an adjustable magnetic counterbalance assembly, comprising: changing the rotational position of a first magnet relative to a second magnet to change the polar alignment of the magnets relative to each other; A method comprising: [Explanation of symbols]

[0051] 20 DOF Stage 21 Counterweight Magnet Assembly 24A Magnet 25A ferromagnetic tube 28 Mobile Table

Claims

1. a first ferromagnetic tube; a first magnet disposed within the first ferromagnetic tube and configured to be axially movable relative to the first ferromagnetic tube; a second magnet movable relative to the first magnet to adjust the counterweight force; 1. An adjustable magnetic counterbalance assembly comprising:

2. The adjustable magnetic counterweight assembly of claim 1 , wherein at least one of the magnets is cylindrical.

3. The adjustable magnetic counterweight assembly of claim 1 , wherein at least one of the magnets is configured to rotate relative to the other magnet such that the polar alignment of the magnets can be changed.

4. 2. The adjustable magnetic counterweight assembly of claim 1, further comprising a second ferromagnetic tube disposed parallel to the first ferromagnetic tube, the second magnet being disposed within the second ferromagnetic tube.

5. The adjustable magnetic counterweight assembly of claim 1 , wherein the first and second magnets are coupled to a first component of a linear motion system.

6. 6. The adjustable magnetic counterweight assembly of claim 5, wherein the first ferromagnetic tube is coupled to a second component of a linear motion system that moves relative to the first component.

7. The adjustable magnetic counterweight assembly of claim 1 , wherein at least one of the magnets is non-cylindrical.

8. The adjustable magnetic counterweight assembly of claim 1 , wherein at least one of the magnets is configured to move closer or farther from the other magnet.

9. 10. The adjustable magnetic counterweight assembly of claim 1, further comprising a third magnet disposed within a third ferromagnetic tube, the third magnet being disposed between the first and second magnets and configured to rotate relative to the first and second magnets.

10. a first ferromagnetic tube disposed adjacent to and parallel to a second ferromagnetic tube; a first magnet disposed within the first ferromagnetic tube and configured to be axially movable relative to the first ferromagnetic tube; a second magnet disposed within the second ferromagnetic tube and configured to be axially movable relative to the second ferromagnetic tube; Equipped with A magnetic counterbalance assembly, wherein the counterbalance force is adjustable by rotating the first and second magnets relative to one another.

11. a third ferromagnetic tube disposed in parallel between the first and second ferromagnetic tubes; The magnetic counterweight assembly of claim 10 , further comprising a third magnet disposed within the third ferromagnetic tube and configured to be axially movable relative to the third ferromagnetic tube.

12. 12. The magnetic counterbalance assembly of claim 11, wherein a first pole of the third magnet is adjacent to the first magnet and a second pole of the third magnet is adjacent to the second magnet to produce a first counterbalance force.

13. 13. The magnetic counterbalance assembly of claim 12, wherein the third magnet is rotatable 90 degrees to produce a second counterbalance force greater than the first counterbalance force.

14. 13. The magnetic counterbalance assembly of claim 12, wherein the third magnet is rotatable 180 degrees to produce a third counterbalance force greater than the second counterbalance force.

15. The magnetic counterbalance assembly of claim 11 , further comprising a counterbalance bracket, the first, second and third magnets being disposed on the counterbalance bracket.

16. 16. The magnetic counterbalance assembly of claim 15, wherein the counterbalance bracket further comprises an adjustment mechanism for rotating the third magnet within the third ferromagnetic tube.

17. 11. The magnetic counterbalance assembly of claim 10, wherein the magnetic counterbalance assembly is a component of a degree-of-freedom (DOF) stage, the first and second ferromagnetic tubes extend through a table arranged on a base of the DOF stage, and the first and second magnets are disposed on a counterbalance bracket arranged on the base.

18. a first ferromagnetic tube; a first magnet disposed within the first ferromagnetic tube and configured to be axially movable relative to the first ferromagnetic tube; Equipped with 1. A magnetic counterbalance assembly for a degree-of-freedom (DOF) motion stage, wherein a counterbalance force is configured to be adjustable by adjusting a position of a first magnet relative to a second magnet disposed within a second ferromagnetic tube.

19. 20. The magnetic counterbalance assembly of claim 18, wherein the magnetic counterbalance assembly is a component of a degree-of-freedom (DOF) stage, the first ferromagnetic tube extends through a table arranged on a base of the DOF stage, and the first magnet is disposed on a counterbalance bracket arranged on the base.

20. a third ferromagnetic tube disposed in parallel between the first and second ferromagnetic tubes; 20. The magnetic counterweight assembly of claim 18, further comprising a third magnet disposed within the third ferromagnetic tube and configured to be axially movable relative to the third ferromagnetic tube.

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