Electromagnetic actuator

Abstract

The invention relates to an electromagnetic actuator (1) comprising two units (2, 3) configured to cause a guiding movement relative to each other in a translation direction (T) and a rotation direction (R) when electromagnetically interacting with a support gap therebetween. The electromagnetic actuator (1) is configured to supply compressed gas to the support gap to build a gas membrane constituting a frictionless floating support between the units (2, 3).

Description

Technical Field

[0001] The invention relates to an electromagnetic actuator with frictionless floating support and a positioning device with the electromagnetic actuator, in particular to a parallel motion positioning device. Background Art

[0002] Known parallel kinematic positioning systems, in particular hexapods, are used to move and precisely position, align and displace loads in all six degrees of freedom, ie three linear axes and three rotational axes. A hexapod comprises six actuators acting together on a single moving platform.

[0003] In prior art hexapods, screw-driven actuators are used to achieve precise positioning. However, these systems often suffer from wear when used in highly repetitive motion applications. In addition, they cannot provide the high acceleration rates and speeds that are often required, such as in motion simulation applications.

[0004] US10,500,676B2 and US11,090,761B2 disclose an electromagnetic actuator with a frictionless air-supported motion guide for the translational movement of a front objective lens in a laser beam focusing subsystem of a laser scanning system. However, these electromagnetic actuators only allow translational movement but prevent rotational movement.

[0005] It would be advantageous to provide an electromagnetic actuator that is capable of moving along a translation axis at high accelerations while still being suitable for use in parallel kinematic positioning systems, particularly hexapods. Summary of the invention

[0006] According to a first aspect, an electromagnetic actuator is provided. The electromagnetic actuator comprises two units, which are configured to cause guided motion relative to each other in a translational direction when electromagnetically interacting, and to cause or allow guided motion relative to each other in a rotational direction. There is a support gap between the two units. The electromagnetic actuator is configured to supply pressurized gas to the support gap to construct a gas film constituting a frictionless floating support between the units. The guided motion relative to each other in the rotational direction can be around the translational direction.

[0007] Passive rotational degrees of freedom can simplify actuation technology and overcome limitations in motion by removing possible over-constraint situations. Active rotational degrees of freedom can increase the versatility of electromagnetic actuators in terms of additional drive options.

[0008] One of the units may be a first unit and the other may be a second unit. The first unit may have a protrusion protruding into the second unit in the translational direction for guiding the movement of the second unit relative to the first unit in the translational direction and in the rotational direction. The second unit may constitute a bushing surrounding the protrusion of the first unit to define a support gap therebetween and / or may be arranged concentrically relative to the protrusion of the first unit. The second unit may have a closed end cap so as to be combined with the first unit to construct a piston with a piston chamber, the piston chamber preferably being supplied with pressurized gas via a piston chamber gas conduit provided or formed in the protrusion.

[0009] The electromagnetic actuator may further comprise a gas supply device having a gas supply terminal and a gas supply channel, the gas supply channel being configured to supply pressurized gas (particularly air) from a gas source (particularly a compressor) to the gas supply terminal and via at least one nozzle gas duct from the gas supply terminal to at least one nozzle arranged in one of the units. Preferably, the bushing comprises at least one nozzle for supplying the pressurized gas to the support gap. The gas supply terminal may form part of one of the units, preferably part of the second unit. At least one of the nozzles or at least one of the nozzle gas ducts may be arranged or formed in the protrusion. It may be advantageous if the protrusion comprises an exhaust groove for discharging the pressurized gas from the support gap or the piston chamber, which is connected to an exhaust duct of the protrusion.

[0010] One of the units (preferably the first unit) may include at least one magnet, and the other of the units (preferably the second unit) may include at least one coil (preferably a voice coil) that interacts with at least one of the magnets by electromagnetic interaction in response to activation of at least one of the coils. At least one of the magnets may be arranged in a housing of the first unit. The housing may be arranged outside the second unit concentrically with respect to the protrusion of the first unit.

[0011] The second unit may include or be configured to accommodate at least one of the coils, the bobbin may be arranged concentrically outside the protruding piece of the first unit, or may protrude into a recess of the housing, the housing having a hollow cylindrical symmetry, the housing accommodating at least one of the magnets. The second unit may include a sleeve arranged concentrically outside the bobbin, for covering at least a portion of the outer surface of the bobbin to provide a sleeve gap therebetween. The electromagnetic actuator may be configured to supply compressed gas to the sleeve gap, in particular for cooling the bobbin or at least one of the coils accommodated by the bobbin. The bobbin may also accommodate the gas supply terminal.

[0012] The sleeve can be rotationally fixed to the spool, preferably by at least two O-rings, in particular elastic O-rings, which generate a clamping force between the spool and the sleeve. The O-rings can be arranged at a distance from each other in the translation direction, so that the sleeve gap can be sealed by the O-rings in the translation direction.

[0013] Alternatively or additionally, the sleeve may be rotationally fixed to the inner sleeve by gluing or welding.

[0014] The electromagnetic actuator may include a power supply device having a power supply terminal and a power supply line, the power supply line being configured to supply power from an energy source to the power supply terminal. The power supply terminal may be connected to at least one of the coils for powering it.

[0015] The units may be configured to limit translational and / or rotational movement relative to each other. The predetermined angular range of rotational movement of the units relative to each other The angle may be between 10 and 350 degrees, preferably between 40 and 320 degrees, and most preferably between 140 and 220 degrees. Each unit may include a stopper, and the stopper may be configured to enter an abutment, thereby limiting the translational and / or rotational movement of the two units relative to each other to a predetermined translational and angular range, respectively.

[0016] The electromagnetic actuator may comprise an encoder, preferably an optical encoder, for encoding the relative position of the two units in at least one of the translational direction and the rotational direction. The encoder may be a linear, incremental or absolute encoder.

[0017] The encoder may comprise at least one optical sensor arranged on one of the units, preferably the first unit. The encoder may also comprise at least one encoder scale arranged on the other of the units, preferably the second unit. The encoder scale may be a grating having detectable lines running along at least one of the translational direction and the rotational direction. The optical sensor may be configured to read at least one of the encoder scales for encoding the relative position of the two units. The encoder may comprise a first sensor configured to interact with a first encoder scale implemented as a grating having lines running in the rotational direction so as to detect the relative translational position of the units. The encoder may alternatively or additionally comprise a second sensor configured to interact with a second encoder scale implemented as a grating having lines running in the translational direction so as to detect the relative rotational position of the units.

[0018] The first and second gratings may be integrally implemented to form a 2D grid on a cylindrical surface, preferably on an outer surface of the sleeve of the second unit or on the outer surface of the bobbin.The second sensor may be located at an angle of about 90 degrees offset from the first sensor in the rotational direction.

[0019] Alternatively, the encoder may have any one of a linear variable differential transformer (LVDT) sensor, a magnetic sensor, an interferometric sensor, and a capacitive sensor.

[0020] The electromagnetic actuator may include a controllable valve configured to control the gas pressure in the piston chamber. During operation of the electromagnetic actuator, the valve may be controlled based on an external load acting on one of the units (preferably the second unit) so as to generate a balancing force on the respective unit to carry a static or passive load. The controllable valve may be an electronic proportional valve.

[0021] The electromagnetic actuator may further include a locking unit for locking the units relative to each other to prevent movement in at least one of the translational direction and the rotational direction. The locking unit may include an expandable collet provided on one of the units (preferably the second unit) and a corresponding opening on the other of the units (preferably the first unit) for receiving an expandable distal end of the expandable collet to at least lock the translational movement of the second unit relative to the first unit.

[0022] During operation of the actuator, the locking unit can be adjusted by reducing the pressure in the expansion collet via a controllable valve so that the force provided by the spring pushes the expandable collet back together into the locked position, thereby providing an internal brake for locking the position of the second unit relative to the first unit.

[0023] One of the units (preferably the first unit) may form a stator, and the other of the units (preferably the second unit) may form a runner or rotor.

[0024] According to a second aspect, a motion or positioning device is provided, comprising a base, a positioning platform and at least one electromagnetic actuator as described above. One of the units is directly or indirectly connected to the base, and another of the units is directly or indirectly connected to the positioning platform. The motion or positioning device may be a parallel motion device, preferably a hexapod.

[0025] Terms and Definitions

[0026] The term "translation direction T" includes opposite directions along the translation axis, preferably any parallel directions.

[0027] The term "rotation direction R" includes opposite directions around the translation axis, in particular along a circular line centered on / arranged concentrically with respect to the translation axis, and preferably any parallel directions.

[0028] The term "translational motion" includes motion in both a forward direction and a rearward direction along a translation axis.

[0029] The term "rotational motion" includes motion in both directions along a circular line concentric with the translation axis.

[0030] The term "or" used herein is generally understood to be an inclusive "or" unless explicitly stated otherwise. For example, the expression "feature A or feature B" shall only include feature A or feature B or the combination of features A and B. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A computer generated exploded perspective view of an electromagnetic actuator representing a first embodiment of the present invention is shown.

[0032] Figure 2 Shown according to Figure 1 Computer generated perspective views of an electromagnetic actuator at different viewing angles and in different states, wherein view (a) depicts the electromagnetic actuator in an extended state, while view (b) depicts the electromagnetic actuator in a retracted or locked and rotated state. It should be emphasized that there is no dependency between the rotational and translational motions, i.e., both motions can be performed independently.

[0033] Figure 3 Shows Figure 1 and 2 Top view of the electromagnetic actuator.

[0034] Figure 4 The electromagnetic actuator is shown along Figure 3 Longitudinal cross-sectional view along line AA defined in FIG.

[0035] Figure 5 A cross-sectional view of an electromagnetic actuator according to a second embodiment of the present invention is shown.

[0036] Figure 6 Two different cross-sectional views of an electromagnetic actuator according to a third embodiment of the invention are shown.

[0037] Figure 7 A front view and a perspective view of a hexapod according to the invention with six electromagnetic actuators are shown. DETAILED DESCRIPTION

[0038] An electromagnetic actuator is described for combining translational and rotational movements of a motion axis in a parallel-kinematic movement or positioning device, preferably in a hexapod. The electromagnetic actuator can alternatively or additionally be used in other motion or positioning systems and motion axis devices which repeat rapid translational movements of an object or element to be moved or positioned, respectively.

[0039] Reference Figures 1 to 4 , shows a two degree of freedom (2DOF) electromagnetic actuator according to the present invention, which provides closed-loop translational positioning and passive rotational motion guided by air bearings.

[0040] The electromagnetic actuator 1 includes a rotor (first unit) 2 and a stator (second unit) 3. The rotor 2 surrounds the stator 3 to allow movement in a translation direction T and a rotation direction R about the translation direction T relative to each other.

[0041] A support gap is provided between the rotor 2 and the stator 3. During operation of the electromagnetic actuator according to the invention, the support gap is supplied with pressurized gas, in particular pressurized air, to build up a gas film constituting a frictionless floating support between the rotor 2 and the stator 3.

[0042] The rotor 2 comprises a housing 4, a projection 5 and an encoder 6. The projection 5 serves, among other things, as a magnetic center pole and is arranged at the distal end of the housing 4. The projection 5 comprises an end cap in the form of a joint 7, which is intended to be connected to an element to be moved or positioned, such as a platform of a hexapod. In the assembled state, the end cap fixes the projection 5 to the distal end of the housing 4, for example by a screw connection or a snap connection. The projection is preferably made of magnetic steel.

[0043] The projection 5 has a projection 8 in the form of a cylinder and projects into the stator 3 in the translation direction T for guiding the movement of the stator 3 relative to the rotor 2 .

[0044] The stator 3 constitutes an air bearing bushing in the form of a bobbin comprising two coils 21 attached to the outer surface of a bobbin 9 separated from one another in the translation direction T. The bobbin 9 is arranged concentrically outside the projection 8 of the lug 5 .

[0045] The sleeve 10 of the stator 3 in the form of an external cylindrical sleeve is concentrically arranged outside the bobbin 9 and covers at least a portion of the outer surface of the bobbin 9 and the coil 21 attached to the bobbin, thereby providing a sleeve gap between the two. The bobbin includes several nozzles 9', which are configured to supply pressurized gas to the sleeve gap and the support gap via nozzle gas ducts (not shown) arranged in the bobbin and conductively connected to the gas supply terminal 22. The bobbin 9 can be made of aluminum (preferably hard anodized aluminum), or brass, or any combination thereof. In particular, the sleeve gap and the support gap are filled with pressurized gas supplied from the same source, in particular pressurized air, so that a gas film constituting a frictionless floating support is constructed in the support gap, while providing gas circulation between the sleeve gap and the support gap, mainly to cool the coil 21 arranged on the outer surface of the bobbin, respectively.

[0046] The sleeve 10 is preferably rotationally fixed to the outer surface of the spool 9 by at least two elastic O-rings 9", which generate a clamping force between the spool 9 and the sleeve 10. The at least two elastic O-rings 9" are arranged at a distance from each other in the translation direction T, so that the sleeve gap is sealed by the O-rings 9" in the translation direction T. Optionally or additionally, the sleeve 10 is rotationally fixed to the outer surface of the spool 9 by gluing or welding. This can prevent loosening of the connection due to aging of the O-rings 9". A closed end cap in the form of a joint 11 is arranged on the distal end of the stator 3 away from the rotor 2 so as to be combined with the rotor 2 to construct a piston with a piston chamber 12, and the joint 11 is intended to be connected to a fixed base element, such as a base plate of a hexapod.

[0047] Each of the rotor 2 and the stator 3 includes a stopper 13, 14. The stoppers 13, 14 are configured to enter an abutment so as to limit the translational and / or rotational movement of the rotor 2 and the stator 3 relative to each other to a predetermined translational and angular range, respectively. Inside.

[0048] With regard to the limitation of the rotational movement R, the housing 4 of the rotor 2 is provided with a stopper 13 which is realized by an unclosed peripheral wall extending from the distal end of the housing 4. The opening of the unclosed peripheral wall receives a stopper 14 realized by an abutment provided on the bobbin 9, so as to limit the rotational movement of the rotor 2 to a predetermined angular range. In the embodiment of the invention, preferably in at least the translationally retracted state of the spool 9 (see Figure 2 and Figure 4 The stops 13, 14 are designed to allow the rotational movement R to reach an angle range between 10 and 350 degrees. Preferably between 40 and 320 degrees, most preferably between 140 and 220 degrees.

[0049] A locking unit is also provided in the electromagnetic actuator 1 for locking the rotor 2 and the stator 3 relative to each other against movement in the translation direction T. In the present embodiment, the locking unit is a non-permanent cantilever snap-on connection. In particular, the locking unit comprises an expandable collet 15 fixed to the joint 11 of the stator 3 and a corresponding opening, which is in particular realized by having at least two boreholes 16, 17 of different diameters in the translation direction T at the center of the protrusion 8 of the protrusion 5. In the retracted / locked position, the expandable distal end 18 of the expandable collet 15 is received in the opening and pops out at the transition from the first borehole 16 with a smaller diameter to the second borehole 17 with a larger diameter, thereby locking the translational movement of the rotor 2 relative to the stator 3.

[0050] During operation of the electromagnetic actuator 1, the locking unit can be adjusted via a controllable valve (not shown) to provide an internal brake for locking the translational position of the rotor 2 relative to the stator 3. In order to transfer the rotor 2 to the locked position, the pressure in the expansion collet 15 and the piston chamber 12 is reduced so that the force provided by the spring 19 pushes the expandable collet 15 back to the locked / retracted position.

[0051] The controllable valve may be an electronic proportional valve configured to control the gas pressure in the piston chamber 12. In this embodiment, the controllable valve is located outside the electromagnetic actuator 1. In other embodiments, the controllable valve forms a part of the electromagnetic actuator 1. For example, the controllable valve may be provided on the bobbin 9.

[0052] Reference Figure 1 and Figure 4 , several permanent magnets 20 are arranged in a circumferential manner on the inner surface of the housing 4 of the rotor 2. Two coils 21 are arranged on the outer surface of the bobbin 9. The coils 21 interact with the magnets 20 in response to activation of the coils 21 to generate translational and / or rotational movement of the stator and the rotor relative to each other.

[0053] The bobbin 9 comprises a gas supply terminal 22 for interacting with a gas supply device 23 and a gas supply line / channel 24, the gas supply line / channel 24 being configured to supply pressurized gas from a gas source to the gas supply terminal 22. In the present embodiment, the gas supply terminal 22 is not only supplied with pressurized gas (in particular pressurized air) for the support gap and / or the sleeve gap, but also with electrical energy for the coil (powering the coil) in order to interact with the magnet 20. The gas supply device 23 comprises at least one nozzle 25 for supplying pressurized gas for cooling reasons to the support gap between the stator 3 and the rotor 2 and / or to the sleeve gap via at least one nozzle gas conduit arranged in the bobbin 9, the pressurized gas being discharged through the nozzle 9'. The pressurized gas is provided from a compressor. The electrical energy is provided from an electrical grid, for example from a public grid.

[0054] Return to reference Figure 1 , the housing 4 of the rotor 2 comprises an opening for receiving an optical encoder 6 for encoding the relative position of the stator 3 and the rotor 2 in at least one of the translation direction T and the rotation direction R. The optical encoder 6 comprises at least one optical sensor 26 interacting with at least one encoder scale 27 provided on the outer surface of the sleeve 10. Preferably, the encoder scale 27 is a grating having detectable lines extending along at least one of the translation direction T and the rotation direction R, wherein the optical sensor 26 is configured to read the at least one encoder scale 27 for encoding the relative position of the stator 3 relative to the rotor 2. The encoder 6 is a linear encoder, preferably one of an incremental or absolute encoder. The encoder scale may be made of aluminum, stainless steel and / or biaxially oriented polyethylene terephthalate.

[0055] Preferably, a first optical sensor 26 is provided, which is configured to interact with a first encoder scale 27, the first encoder scale 27 being implemented as a grating having parallel lines / rings extending in the rotational direction so as to detect the relative translational position between the stator 3 and the rotor 2; and a second sensor 26 is provided, which is configured to interact with a second encoder scale 27, the second encoder scale 27 being implemented as a grating having parallel lines extending in the translational direction so as to detect the relative rotational position between the stator 3 and the rotor 2.

[0056] In other embodiments, the first grating and the second grating are integrally implemented to form a 2D grid.The second sensor 26 is located at an angle of approximately 90 degrees offset from the first sensor 26 in the rotational direction.

[0057] Figure 5A second embodiment of the electromagnetic actuator 1 according to the present invention is shown in a cross-sectional view. Figures 1 to 4 Some details of the electromagnetic actuator shown in FIG. 1 are substantially the same or at least similar to those contained in the electromagnetic actuator according to the second embodiment. Figure 5 A second embodiment of the electromagnetic actuator will be described below only with reference to Figures 1 to 4 The difference from the first embodiment.

[0058] The protrusion 5 of the first unit 2 of the electromagnetic actuator 1 is surrounded or surrounded by the inner wall portion of the second unit 3, which defines an inner hollow cylindrical portion or bushing. The inner wall portion serves as a magnetic center pole and an air bearing surface and is made of magnetic steel. The protrusion 5 or its protrusion 8, respectively, is made of aluminum and serves as an air bearing shaft and has a nozzle (not shown) for discharging compressed gas guided to the nozzle via a nozzle gas duct (also not shown) in the protrusion 8, thereby building a compressed gas film between the protrusion 5 and the air bearing surface in the corresponding air bearing gap.

[0059] A bobbin 9 made of aluminum is arranged at or attached to the first unit 2. The bobbin 9 accommodates a coil 21. The bobbin 9 protrudes into another (outer) hollow cylindrical portion of the second unit 3, which is arranged between an inner wall portion defining the inner hollow cylindrical portion and an outer wall portion of the second unit 3. The outer wall portion of the second unit 3 accommodates several circumferentially arranged permanent magnets 20 and is made of magnetic steel constituting the housing 4 or at least the housing portion of the second unit 3. The permanent magnets 20 are intended to interact with the coil 21 upon electrical excitation with a magnetic gap therebetween.

[0060] For balancing reasons, the piston chamber 12 is supplied with pressurized gas via a separate piston chamber gas duct (not shown), which is preferably provided in the projection 8 of the projection 5 and has an outlet or nozzle at the end of the projection 8 adjacent to the piston chamber 12 .

[0061] An exhaust groove (not shown) is circumferentially disposed near but spaced from the end of the projection 8 for exhausting pressurized gas from the air bearing gap and the piston chamber 12 and is conductively connected to an exhaust conduit (not shown).

[0062] Figure 6 A third embodiment of an electromagnetic actuator 1 according to the invention is shown in two different cross-sectional views. Here again, for the sake of clarity or simplicity, the respective Figures 1 to 4 Some details of the electromagnetic actuator shown in FIG. 1 are substantially the same or at least similar to those contained in the electromagnetic actuator according to the third embodiment. Figure 6 A third embodiment of the electromagnetic actuator will be described below only with reference to Figures 1 to 4 The difference from the first embodiment.

[0063] The protrusion 5 or protrusion 8 of the first unit 2 of the electromagnetic actuator 1 is surrounded or encircled by a portion of the second unit 3, which is substantially formed as a hollow cylinder or cylindrical bushing made of aluminum. Said hollow cylindrical portion of the second unit 3 accommodates the coil 21 in a circumferential manner, thereby establishing a bobbin 9. Furthermore, the second unit 3 accommodates a cylindrical sleeve 10 arranged coaxially on its outside, the surface of the sleeve 10 being flush with the surface of the second unit 3 adjacent to the sleeve. The sleeve 10 accommodates an encoder scale 27 for interaction with a corresponding optical sensor 26.

[0064] The protrusion 5 or its protrusion 8 respectively serves as a magnetic center pole and an air support shaft having a nozzle 9' for discharging compressed gas guided to the nozzle via a nozzle gas duct (not shown) in the protrusion 8. The second unit 3 or its hollow cylindrical part surrounding the protrusion 8 serves as an air support bushing and is complementary to the air support shaft realized by the protrusion 8, and the compressed gas or air is discharged from the nozzle 9' and directed to the air support gap between the air support bushing and the air support gap, thereby forming a compressed gas film between them.

[0065] A housing part or housing 4 made of magnetic steel is arranged at or attached to the second unit 3 and houses several permanent magnets 20 arranged circumferentially inside the housing 4 and surrounding or enclosing a coil 21 of the bobbin 9. Furthermore, the housing 4 surrounds or encloses a major part of the sleeve 10 and houses an optical sensor 26 that interacts with an encoder scale 27 attached to or integrally formed with the sleeve 10. The housing 4 or the housing part may be made an integral part of the second unit 3.

[0066] The end of the bobbin 9 of the second unit 3 forms together with the end of the projection 8 of the projection 5 a piston chamber 12. For reasons of balance, the piston chamber 12 is supplied with pressurized gas via a separate piston chamber gas duct 28 provided in the projection 8, which duct 28 has an outlet or nozzle at the end of the projection 8 adjacent to the piston chamber 12. An exhaust groove 30 is provided in a circumferential manner near the end of the projection 8 but spaced therefrom for exhausting pressurized gas from the air bearing gap and from the piston chamber 12, the exhaust groove being conductively connected to the exhaust duct 32.

[0067] At respective ends of the first unit 2 and the second unit 3, respective joints 7 or 11 are arranged for connection with another element, such as an element to be moved or positioned or a fixed base element.

[0068] Figure 7A parallel-kinematic positioner 34 in the form of a hexapod comprising six electromagnetic actuators 1 as described above is shown in two different views.

[0069] Reference numerals list

[0070] 1 Electromagnetic actuator

[0071] Unit 2

[0072] 3Unit 2

[0073] 4 (housing of the first unit 2 or the second unit 3)

[0074] 5 protruding parts

[0075] 6 Encoder

[0076] 7, 11 connector

[0077] 8 (of the protruding member 5) protrusion

[0078] 9 Spools

[0079] 9' (spool 9) nozzle

[0080] 9" (attached to spool 9) O-ring

[0081] 10 sleeves

[0082] 12 Piston chamber

[0083] 13, 14 stopper

[0084] 15 Expandable chuck

[0085] 16, 17 drilling

[0086] 18 (expandable distal end of expandable chuck 15)

[0087] 19 Spring

[0088] 20 Magnets

[0089] 21 coils

[0090] 22 Gas supply terminal

[0091] 23 Gas supply device

[0092] 24 Gas supply lines

[0093] 25 Nozzles

[0094] 26 optical sensors

[0095] 27 encoder scale

[0096] 28 Piston chamber gas conduit

[0097] 30 Exhaust slots

[0098] 32 Exhaust duct

[0099] 34 Parallel motion positioner

Claims

1. An electromagnetic actuator (1) comprising two units (2, 3) which are configured to cause guided movement relative to each other in a translation direction (T) when electromagnetically interacting, and to cause or allow guided movement relative to each other in a rotation direction (R), preferably around the translation direction (T), with a support gap between them, wherein the electromagnetic actuator (1) is configured to supply pressurized gas to the support gap to build a gas film constituting a frictionless floating support between the units (2, 3).

2. The electromagnetic actuator (1) according to claim 1, characterized in that One of the units (2) is a first unit (2), and the other of the units (2, 3) is a second unit (3), wherein the first unit (2) has a protruding piece (5) protruding into the second unit (3) in the translation direction, for guiding the movement of the second unit (3) relative to the first unit (2) in the translation direction (T) and the rotation direction (R), wherein the second unit (3) preferably constitutes a bushing surrounding the protruding piece (5) of the first unit (2) to define the support gap therebetween, and / or is arranged concentrically relative to the protruding piece of the first unit (2), wherein the second unit (3) preferably has a closed end cover so as to be combined with the first unit (2) to construct a piston having a piston chamber (12), and the piston chamber (12) is configured to be supplied with pressurized gas, in particular air.

3. Electromagnetic actuator (1) according to any one of the preceding claims, characterized in that The actuator (1) further comprises a gas supply device (23), the gas supply device (23) having a gas supply terminal (22) and a gas supply channel (24), the gas supply channel (24) being configured to supply pressurized gas, in particular air, from a gas source, in particular a compressor, to the gas supply terminal (22), and via at least one nozzle gas conduit from the gas supply terminal (22) to at least one nozzle (9') arranged in one of the units (2, 3), the at least one nozzle (9') being configured to supply the pressurized gas to the support gap, wherein preferably, the gas supply terminal (22) forms part of one of the units (2, 3).

4. The electromagnetic actuator (1) according to claim 3, characterized in that At least one of the nozzles (9') or at least one of the nozzle gas ducts is arranged in the protrusion (5).

5. The electromagnetic actuator (1) according to claim 3 or 4, characterized in that: The projection (5) includes an exhaust groove (30) connected to an exhaust conduit (32) of the projection (5), the exhaust groove (30) being configured to exhaust pressurized gas from the support gap and the piston chamber (12).

6. Electromagnetic actuator (1) according to any one of the preceding claims, characterized in that One of the units (2, 3) comprises at least one magnet (20), and the other of the units (2, 3) comprises at least one coil (21), preferably a voice coil, which interacts with at least one of the magnets (20) by electromagnetic interaction in response to activation of the at least one coil (21), wherein preferably, at least one of the magnets (20) is arranged in a housing (4) of one of the units (2, 3), the housing being arranged concentrically with respect to the protrusion (5) of the first unit (2).

7. The electromagnetic actuator (1) according to any one of the preceding claims 2 to 6, characterized in that The second unit (3) includes or is designed as a bobbin (9) which is arranged concentrically relative to the protruding piece (5), and the bobbin accommodates at least one coil (21).

8. The electromagnetic actuator (1) according to claim 7, characterized in that The bobbin protrudes into a recess of the housing (4), which has a hollow cylindrical symmetry and accommodates at least one of the magnets (20).

9. The electromagnetic actuator (1) according to claim 7 or 8, characterized in that: A sleeve (10) is concentrically arranged outside the bobbin (9) for covering at least a portion of the outer surface of the bobbin (9) to provide a sleeve gap therebetween, wherein at least one of the coils (21) is arranged between the bobbin (9) and the sleeve (10).

10. The electromagnetic actuator according to claim 9, characterized in that: The electromagnetic actuator (1) is configured to supply compressed gas to the sleeve gap, in particular for cooling the bobbin (9) or at least one of the coils (21), wherein preferably the bobbin (9) accommodates the gas supply terminal (22) according to claim 3.

11. The electromagnetic actuator (1) according to claim 9 or 10, characterized in that: The sleeve (10) is preferably rotationally fixed on the spool (9) by at least two O-rings (9"), in particular elastic O-rings (9"), which generate a clamping force between the spool (9) and the sleeve (10), wherein the O-rings (9") are arranged at a distance from each other in the translation direction (T) so that the sleeve gap is sealed by the O-rings (9") in the translation direction (T).

12. Electromagnetic actuator (1) according to any one of the preceding claims, characterized in that The units (2, 3) are configured to limit translational and / or rotational movement relative to each other, wherein preferably, the predetermined angular range (φ) of the rotational movement (R) of the units (2, 3) relative to each other is between 10 and 350 degrees, preferably between 40 and 320 degrees, most preferably between 140 and 220 degrees, wherein preferably, each unit (2, 3) comprises a stopper (13, 14), and the stopper (13, 14) is configured to enter the abutment (13, 14) so ​​as to limit the translational and / or rotational movement of the two units (2, 3) relative to each other to the predetermined translational and angular ranges (φ), respectively.

13. Electromagnetic actuator (1) according to any one of the preceding claims, characterized in that The actuator (1) comprises an encoder (6), preferably an optical encoder, for encoding the relative position of the two units (2, 3) in at least one of the translation direction (T) and the rotation direction (R), wherein the encoder (6) is preferably a linear, incremental or absolute encoder.

14. Electromagnetic actuator according to the preceding claim, characterized in that The encoder (6) comprises at least one optical sensor (26) arranged on one of the units (2, 3) and at least one encoder scale (27) arranged on the respective other of the units (2, 3), wherein the encoder scale (27) is preferably a grating having detectable lines extending along at least one of the translation direction (T) and the rotation direction (R), wherein the optical sensor (26) is configured to read the at least one encoder scale (27) for encoding the relative position of the two units (2, 3), wherein preferably there is a first sensor and a second sensor, the first sensor being configured to interact with a first encoder scale implemented as a grating having lines extending in the rotation direction in order to detect the relative translation position of the units (2, 3), and the second sensor being configured to interact with a second encoder scale implemented as a grating having lines extending in the translation direction in order to detect the relative rotation position of the units (2, 3).

15. Electromagnetic actuator according to the preceding claim, characterized in that The first grating and the second grating are integrally implemented to form a 2D grid on a cylindrical surface, preferably on the outer surface of a bobbin according to claim 7 or 8, or on the outer surface of a sleeve (10) according to claims 9 to 11, wherein preferably, the second sensor is located at an angle of approximately 90 degrees offset from the first sensor in the rotation direction.

16. Electromagnetic actuator (1) according to any one of the preceding claims 3 to 15, characterized in that The actuator further comprises a locking unit (15) for locking the units (2, 3) relative to each other to prevent movement in at least one of the translational direction (T) and the rotational direction (R), wherein the locking unit (15) preferably comprises an expandable clamp arranged on one of the units (2, 3) and a corresponding opening on the corresponding other of the units (2, 3) for receiving the expandable distal end of the expandable clamp to at least lock the translational movement of one of the units (2, 3) relative to the corresponding other of the units (2, 3), and the locking unit is configured to be supplied with pressurized gas by the gas supply device (23).

17. Electromagnetic actuator (1) according to the preceding claim, characterized in that The locking unit (15) can be adjusted during operation of the actuator (1) by reducing the pressure in the expansion clamp via a controllable valve so that the force provided by the spring pushes the expandable clamps back together into a locked position, thereby providing an internal brake for locking the position of one of the units (2, 3) relative to the corresponding other of the units (2, 3).

18. Electromagnetic actuator (1) according to any one of the preceding claims 3 to 17, characterized in that The piston chamber (12) is configured to be supplied with pressurized gas by the gas supply device (23), preferably through a piston chamber gas conduit (28) provided in the protruding member (5), wherein the pressure of the pressurized gas in the piston chamber (12) can be adjusted via an electronic proportional valve.

19. Electromagnetic actuator (1) according to any one of the preceding claims, characterized in that One of the units (2, 3) forms a runner or rotor, and the other of the units (2, 3) forms a stator.

20. A positioning device comprising a base, a positioning platform and at least one electromagnetic actuator (1) according to any one of the preceding claims, wherein one of the units (2, 3) is connected to the base and the other of the units (2, 3) is connected to the positioning platform.

21. The positioning device according to claim 20, characterized in that The positioning device corresponds to a parallel motion manipulator (34), preferably to a hexapod with six electromagnetic actuators (1).

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