A Maxwell force-driven three-degree-of-freedom electromagnetic actuator and its control method

Abstract

This invention discloses a Maxwell force-driven three-degree-of-freedom electromagnetic actuator and its control method. Four sets of permanent magnets are evenly distributed around the mover, and the permanent magnets are respectively connected to magnetic guide shoes and stator magnetic arms located obliquely above and below the side wall of the mover. An excitation coil is wound on the stator magnetic arm, which is connected to a magnetic guide base. The magnetic guide base is connected to a magnetic guide column, which extends into the interior of the mover and is fixed in the middle of a flexible diaphragm. The flexible diaphragm is connected to the mover. The permanent magnets, magnetic guide shoes, stator magnetic arms, magnetic guide base, and magnetic guide column together constitute a magnetic circuit system, enabling the mover to simultaneously respond to three independent current excitation modes, realizing integrated parallel drive of rotation around the X-axis and Y-axis and translation along the Z-axis. This invention solves the problems of structural redundancy, lack of degrees of freedom, contradiction between motion range and linear drive, and control coupling in existing electromagnetic actuators through the design of "three-degree-of-freedom integrated magnetic circuit topology" and "misaligned mover-stator configuration".

Description

Technical Field

[0001] This invention relates to the field of precision drive technology, specifically to a Maxwell force-driven three-degree-of-freedom electromagnetic actuator and its control method. Background Technology

[0002] Precision actuators, as one of the fundamental core components of micro-actuation, micro-measurement, and micro-manufacturing, are widely used in precision machining, space communication, optical engineering, robotics, and aerospace. However, traditional voice coil motor actuators suffer from low power density, failing to meet the design requirements of minimizing size, weight, and power consumption; piezoelectric ceramic actuators have small actuation strokes, making them unsuitable for millimeter-level large-stroke precision actuation applications. Electromagnetic actuation technology, utilizing Maxwell's electromagnetic force principle, is considered an effective solution that simultaneously achieves high power density and large actuation stroke, and is increasingly being applied to high-end electromechanical systems such as high-speed mirror systems, imaging optical scanning systems, high-speed tool servos, and robots.

[0003] In the field of precision drives, Maxwell's electromagnetic force (the attractive force between magnets along the direction of magnetic flux, the magnitude of which is proportional to the square of the magnetic flux density) is used to construct high-power-density actuators. To improve the nonlinear relationship between force and current, a known technique is to introduce a permanent magnet bias magnetic field: a constant bias flux is pre-established in the working air gap, and a control current is passed through the excitation coil to generate a control flux. The superposition of these two forces allows the generated Maxwell's force to be approximately linearly related to the coil current. Such actuators are also known as normal-stress motors and show potential in applications requiring large strokes and high response speeds (such as fast-reflecting mirrors and precision positioning stages).

[0004] Existing Maxwell electromagnetic actuators have the following main drawbacks:

[0005] (1) Low integration of multiple degrees of freedom and redundant structure: To achieve multi-degree-of-freedom motion, existing technologies usually use multiple single-degree-of-freedom actuators in mechanical series (such as Chinese patent application CN116455173A) or simple planar parallel stacking. This approach results in a complex overall actuator structure, large size, and increased mass of moving parts, which is not conducive to the miniaturization and weight reduction of the system, and will reduce the dynamic response speed.

[0006] (2) Lack of integrated three-axis fully active drive solution: Some existing technologies (such as Chinese patent application CN111427148A) have achieved compact parallel drive of two degrees of freedom (such as rotation around the X and Y axes) through magnetic circuit design optimization. However, such solutions have failed to further integrate the drive capability of the third axis (such as translation around the Z axis). In order to obtain complete three-dimensional motion, it is still necessary to introduce additional independent drive units, and it is impossible to achieve a truly "integrated" three-degree-of-freedom integrated design.

[0007] (3) There is a contradiction between the range of motion and the linear drive characteristics: The motion (translation or rotation) of the mover in a traditional Maxwell actuator directly causes a significant change in the working air gap length between it and the stator. According to Maxwell's principle of force, this will cause the driving force / torque to have a strong nonlinear relationship with the displacement / rotation angle. If the initial air gap is increased in order to pursue a large range of motion, it will aggravate magnetic flux leakage and nonlinearity, making it difficult to achieve high-precision linear control. It is necessary to rely on complex nonlinear compensation, which increases the complexity and instability of the control system.

[0008] (4) Control coupling problem: In a system composed of multiple independent actuators, there may be mechanical interference or assembly errors between the actuators of each degree of freedom, resulting in control coupling. Driving a single degree of freedom may unintentionally affect the state of other degrees of freedom, requiring dynamic decoupling control, which increases the complexity of the control algorithm and the real-time computation burden.

[0009] The core of the drawbacks (1) and (2) lies in the contradiction between the existing magnetic circuit topology and the multi-degree-of-freedom decoupled drive. The series scheme is essentially a physical stacking, which inevitably leads to an increase in volume and weight. In the existing two-axis parallel scheme, the magnetic circuit layout (such as an orthogonal C-type magnetic circuit) is optimized to generate axial torque. The symmetry design of its magnetic flux path does not consider how to efficiently and independently generate a pure axial (Z-direction) thrust. Therefore, it is difficult to naturally extend the third axis drive capability without significantly changing the structure.

[0010] The fundamental reason for the drawback (3) lies in the direct coupling between the kinematic and electromagnetic models. In the traditional "face-to-face" or "opposite" moving-stator configuration, the displacement or rotation coordinates of the mover are directly related to the key electromagnetic parameter of the working air gap length. As long as this direct relationship exists, there is an inherent conflict between the large-stroke motion and the linearity and controllability of force / torque.

[0011] Disadvantage (4) is a system-level problem derived from disadvantages (1) and (2). The non-independence of the physical structure inevitably leads to the coupling of control. Summary of the Invention

[0012] This invention provides a Maxwell force-driven three-degree-of-freedom electromagnetic actuator and its control method, aiming to solve the technical problem that existing electromagnetic actuators are difficult to achieve parallel, wide-range, and high-precision driving of three degrees of freedom—rotation about the X-axis (θx), rotation about the Y-axis (θy), and translation along the Z-axis (Z)—within a compact structure.

[0013] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0014] A Maxwell force-driven three-degree-of-freedom electromagnetic actuator includes: a mover, permanent magnets, magnetic shoes, stator arms, excitation coils, a magnetic base, a magnetic column, and a flexible diaphragm; four sets of permanent magnets are circumferentially distributed around the mover, with the upper N pole of each set of permanent magnets connected to a magnetic shoe, and the lower S pole of each set of permanent magnets connected to the top of a stator arm; the magnetic shoes are located diagonally above the sidewall of the mover, and the stator arms are located diagonally below the sidewall of the mover, such that the rotation center of the mover is located in the middle plane of the permanent magnets; each stator arm has an independently wound excitation coil, and the bottom of the stator arm... The end is connected to the mounting groove of the magnetic base; the middle part of the magnetic base is connected to the vertically arranged magnetic column, the top of the magnetic column extends to the Z-direction center plane of the internal cavity of the mover and is fixed to the middle of the flexible diaphragm; the edge of the flexible diaphragm is connected to the mounting boss in the internal cavity of the mover; the four sets of permanent magnets and magnetic shoes, four stator magnetic arms, magnetic base and magnetic column together constitute a magnetic circuit system, so that the mover can respond to three independent current excitation modes at the same time, thereby realizing the integrated parallel drive of three degrees of freedom: rotation around the X-axis (θx), rotation around the Y-axis (θy) and translation along the Z-axis (Z).

[0015] As a further improvement of the present invention, the moving part is provided with top and bottom chamfers on all four sides.

[0016] As a further improvement of the present invention, the excitation coils on the four stator magnetic arms can be driven independently, and an insulating layer is provided between the excitation coils and the stator magnetic arms.

[0017] As a further improvement of the present invention, the stator magnetic arm adopts a split structure or an integrated molding structure; the magnetic base adopts a split structure or an integrated molding structure; and the magnetic column adopts a split structure or an integrated molding structure.

[0018] As a further improvement of the present invention, the mover, magnetic shoe, stator arm, magnetic base, and magnetic column are all made of soft magnetic material; the permanent magnet is made of neodymium iron boron or ferrite material; and the flexible diaphragm is made of titanium alloy material.

[0019] As a further improvement of the present invention, the permanent magnet and the magnetic shoe, the permanent magnet and the stator arm, and the stator arm and the magnetic base are all fixed by adhesive bonding.

[0020] As a further improvement of the present invention, the permanent magnet includes a first permanent magnet, a second permanent magnet, a third permanent magnet and a fourth permanent magnet, and the magnetic shoe includes a first magnetic shoe, a second magnetic shoe, a third magnetic shoe and a fourth magnetic shoe;

[0021] The stator magnetic arm includes a first stator magnetic arm, a second stator magnetic arm, a third stator magnetic arm, and a fourth stator magnetic arm that are evenly distributed around the outer periphery of the mover in sequence. A first excitation coil is wound on the first stator magnetic arm, a second excitation coil is wound on the second stator magnetic arm, a third excitation coil is wound on the third stator magnetic arm, and a fourth excitation coil is wound on the fourth stator magnetic arm.

[0022] There are constant air gaps between the upper part of the outer wall of the mover and the permanent magnet and the magnetic shoe, and between the mover and the magnetic column. There are working air gaps between the lower part of the outer wall of the mover and the permanent magnet and the stator arm.

[0023] The magnetization direction of the permanent magnet is vertically upward. A first bias magnetic flux is formed between the first permanent magnet, the first magnetic shoe, the mover, and the first stator magnetic arm. A second bias magnetic flux is formed between the second permanent magnet, the second magnetic shoe, the mover, and the second stator magnetic arm. A third bias magnetic flux is formed between the third permanent magnet, the third magnetic shoe, the mover, and the third stator magnetic arm. A fourth bias magnetic flux is formed between the fourth permanent magnet, the fourth magnetic shoe, the mover, and the fourth stator magnetic arm.

[0024] As a general technical concept, the present invention also provides a control method applicable to the above-mentioned Maxwell force-driven three-degree-of-freedom electromagnetic actuator. The control of the three-degree-of-freedom electromagnetic actuator includes rotation (θx) control about the X-axis: when an excitation current in a preset direction is applied to the first excitation coil and the second excitation coil, an upward control magnetic flux is generated in the first stator magnetic arm and a downward control magnetic flux is generated in the second stator magnetic arm; the control magnetic flux flows into the mover from the first working air gap between the mover and the first stator magnetic arm, and flows out of the mover from the second working air gap between the mover and the second stator magnetic arm. After being superimposed with the first bias magnetic flux and the second bias magnetic flux, the magnetic field in the first working air gap is weakened and the magnetic field in the second working air gap is strengthened; the electromagnetic force on the mover on the first stator magnetic arm side decreases and the electromagnetic force on the second stator magnetic arm side increases, thereby generating a positive rotational torque about the X-axis.

[0025] As a further improvement of the present invention, the control of the three-degree-of-freedom electromagnetic actuator also includes rotation (θy) control around the Y-axis: when an excitation current in a preset direction is applied to the third excitation coil and the fourth excitation coil, an upward control flux is generated in the third stator magnetic arm and a downward control flux is generated in the fourth stator magnetic arm; the control flux flows into the mover from the third working air gap and flows out of the mover from the fourth working air gap, and after being superimposed with the third bias flux and the fourth bias flux, the magnetic field in the third working air gap weakens and the magnetic field in the fourth working air gap strengthens; the electromagnetic force on the mover on the third stator magnetic arm side decreases and the electromagnetic force on the fourth stator magnetic arm side increases, thereby generating a positive rotational torque around the Y-axis.

[0026] As a further improvement of the present invention, the control of the three-degree-of-freedom electromagnetic actuator also includes translational (Z) control along the Z-axis: when a preset direction current is applied to the first excitation coil and the second excitation coil, and a preset direction current is also applied to the third excitation coil and the fourth excitation coil, an upward control magnetic flux is generated in the first stator magnetic arm, the second stator magnetic arm, the third stator magnetic arm and the fourth stator magnetic arm; the control magnetic flux flows into the mover from the lower periphery, flows out from the middle region of the mover and enters the magnetic column, and after superimposing with the first bias magnetic flux, the second bias magnetic flux, the third bias magnetic flux and the fourth bias magnetic flux, the magnetic field in all working air gaps is uniformly weakened; the electromagnetic force on the lower periphery of the mover is reduced, while the electromagnetic force on the upper side remains unchanged, thereby generating a net electromagnetic resultant force along the Z-axis.

[0027] Compared with the prior art, the Maxwell force-driven three-degree-of-freedom electromagnetic actuator and its control method of the present invention have the following significant advantages:

[0028] 1. A highly integrated three-degree-of-freedom integrated drive solution is provided: a novel magnetic circuit topology is designed so that a single stator-motor system can respond to three independent current excitation modes, which correspond to and can effectively drive the motion of the three degrees of freedom θx, θy and Z, respectively. This physically realizes a true "integrated" three-axis parallel drive, eliminating the volume, weight and inertial burden caused by mechanical series connection.

[0029] 2. Achieved large-angle deflection and translational stroke: An innovative design of the relative positional relationship between the mover and stator (such as a "misalignment" design) ensures that the length of the key working air gap region, which generates effective Maxwell forces between the mover and stator, remains essentially constant or changes minimally during rotational motion. This decouples the "range of motion" from "harmful nonlinear air gap changes," thereby achieving a range of motion far exceeding that of traditional solutions while maintaining a good linear relationship between driving force / torque and control current.

[0030] 3. A foundation for low coupling and easy control has been established: Through the above magnetic circuit and structural design, the control magnetic flux paths corresponding to the three degrees of freedom are decoupled as much as possible in space, reducing cross coupling at the physical level, and laying the foundation for designing simple, efficient and high-precision independent three-axis control algorithms or composite trajectory tracking control. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure and principle of the three-degree-of-freedom electromagnetic actuator in a specific embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the exploded structure principle of a three-degree-of-freedom electromagnetic actuator in a specific embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the magnetic circuit principle of the θx axis in a specific embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the θy-axis magnetic circuit principle in a specific embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the Z-axis magnetic circuit in the YOZ plane in a specific embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the Z-axis magnetic circuit in the XOZ plane in a specific embodiment of the present invention;

[0037] Figure 7 This is a simplified schematic diagram of the magnetic circuit along the θx axis in a specific embodiment of the present invention;

[0038] Figure 8 This is a simplified schematic diagram of the θy-axis magnetic circuit in a specific embodiment of the present invention;

[0039] Figure 9 This is a simplified schematic diagram of the Z-axis magnetic circuit in the YOZ plane in a specific embodiment of the present invention;

[0040] Figure 10 This is a simplified schematic diagram of the Z-axis magnetic circuit in the XOZ plane in a specific embodiment of the present invention.

[0041] Legend: 1. Moving element; 101. Mounting boss; 2. Permanent magnet; 3. Magnetic guide shoe; 31. First magnetic guide shoe; 32. Second magnetic guide shoe; 33. Third magnetic guide shoe; 34. Fourth magnetic guide shoe; 4. Stator magnetic arm; 41. First stator magnetic arm; 42. Second stator magnetic arm; 43. Third stator magnetic arm; 44. Fourth stator magnetic arm; 5. Excitation coil; 51. First excitation coil; 52. Second excitation coil; 53. Third excitation coil; 54. Fourth excitation coil; 6. Magnetic guide base; 601. Mounting slot; 7. 8. Magnetic guide column; 9. Flexible diaphragm; 10. Connecting screw; 11. Fastening screw; 12. Mounting screw; 121. First bias magnetic flux; 122. Second bias magnetic flux; 123. Third bias magnetic flux; 124. Fourth bias magnetic flux; 131. First constant air gap; 132. Second constant air gap; 133. Third constant air gap; 134. Fourth constant air gap; 141. First working air gap; 142. Second working air gap; 143. Third working air gap; 144. Fourth working air gap; 15. Control magnetic flux; 16. Interval air gap. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0043] In the description of this invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0045] Example

[0046] like Figure 1 and Figure 2 As shown, the Maxwell force-driven three-degree-of-freedom electromagnetic actuator of the present invention includes a mover 1, four sets of rectangular permanent magnets 2 and magnetic shoes 3, four sets of stator magnetic arms 4 and excitation coils 5, a magnetic base 6 and a magnetic column 7, and a flexible diaphragm 8. The four sets of permanent magnets 2 are evenly distributed around the mover 1. The upper N pole of each set of permanent magnets 2 is connected to a magnetic shoe 3, and its lower S pole is connected to the top of a stator magnetic arm 4. Crucially, the magnetic shoes 3 are located diagonally above the sidewall of the mover 1, rather than directly to the side or above it, and the stator magnetic arms 4 are located diagonally below the sidewall of the mover 1, rather than directly to the side or below it, so that the rotation center of the mover 1 is approximately located in the plane of the middle of the permanent magnets 2, specifically in the middle of the inner cavity of the mover 1. This is the so-called "misalignment" design, which ensures minimal change in the air gap length when the mover 1 deflects. The bias magnetic flux generated by permanent magnet 2 is designed to be injected obliquely above and out obliquely below mover 1, forming a specific spatial distribution. Within the symmetrical working air gap, the magnitude of the bias magnetic flux is equal, but the flow direction of the flux relative to the mover exhibits a specific combination of symmetry and antisymmetry; for example, all flux flows in on one side and all flux flows out on the other side. This unique bias magnetic field distribution is the physical basis for subsequently controlling the linear superposition of magnetic flux to independently generate pure torque or pure thrust.

[0047] In this embodiment, each stator arm 4 is independently wound with an excitation coil 5 and is driven independently. The bottom ends of all stator arms 4 are connected to the mounting slots 601 around the magnetic base 6, and the middle part of the magnetic base 6 is connected to the vertically arranged magnetic column 7 by mounting screws 11. The top end of the magnetic column 7 extends to the Z-axis center plane of the internal cavity of the mover 1 and is fixed to the middle part of the flexible diaphragm 8 by fastening screws 10. The four edges of the flexible diaphragm 8 are connected to the four mounting bosses 101 in the internal cavity of the mover 1 by connecting screws 9. Through the connection method of the flexible diaphragm 8, the X and Y axis translational degrees of freedom and the rotational degrees of freedom about the Z axis of the mover 1 are constrained, so that it retains only three degrees of motion freedom: rotation about the X axis (θx), rotation about the Y axis (θy), and translation along the Z axis (Z).

[0048] A magnetically guided column 7 is positioned at the central axis of the mover 1 cavity and connected to the magnetically guided base 6. The magnetically guided column 7 not only serves as mechanical support for the flexible diaphragm 8, but more importantly, it provides a low-resistivity closed path for the control flux in the Z-axis translational control mode. During Z-axis drive, the control flux flows into the mover 1 from the surrounding stator magnetic arms 4 and then returns through the magnetically guided column 7, thereby efficiently generating net thrust along the Z-axis. The placement of the magnetically guided column 7 is a core structural feature for achieving compact, high-thrust Z-axis drive.

[0049] In this embodiment, the permanent magnet 2 includes a first permanent magnet 21, a second permanent magnet 22, a third permanent magnet 23, and a fourth permanent magnet 24; the magnetic guide shoe 3 includes a first magnetic guide shoe 31, a second magnetic guide shoe 32, a third magnetic guide shoe 33, and a fourth magnetic guide shoe 34; the stator magnetic arm 4 includes a first stator magnetic arm 41, a second stator magnetic arm 42, a third stator magnetic arm 43, and a fourth stator magnetic arm 44, which are sequentially and evenly distributed around the outer periphery of the mover 1; a first excitation coil 51 is wound on the first stator magnetic arm 41, a second excitation coil 52 is wound on the second stator magnetic arm 42, a third excitation coil 53 is wound on the third stator magnetic arm 43, and a fourth excitation coil 54 is wound on the fourth stator magnetic arm 44.

[0050] Furthermore, sufficient working air gaps need to be reserved between the outer wall of the mover 1 and the permanent magnet 2 and the magnetic guide shoe 3, as well as between the inner wall of the mover 1 cavity and the outer wall of the magnetic guide column 7, to ensure that there is no mechanical interference when the mover 1 moves in three degrees of freedom. Specifically, a first constant air gap 131 is reserved between the outer wall of the mover 1 and the first permanent magnet 21 and the first magnetic guide shoe 31; a second constant air gap 132 is reserved between the outer wall of the mover 1 and the second permanent magnet 22 and the second magnetic guide shoe 32; a third constant air gap 133 is reserved between the outer wall of the mover 1 and the third permanent magnet 23 and the third magnetic guide shoe 33; and a fourth constant air gap 134 is reserved between the outer wall of the mover 1 and the fourth permanent magnet 24 and the fourth magnetic guide shoe 34; and an interval air gap 16 is reserved between the inner wall of the mover 1 cavity and the outer wall of the magnetic guide column 7.

[0051] In this embodiment, the magnetization direction of the permanent magnet 2 is vertically upward. A first bias magnetic flux 121 is formed between the first permanent magnet 21, the first magnetic guide shoe 31, the mover 1 and the first stator magnetic arm 41. A second bias magnetic flux 122 is formed between the second permanent magnet 22, the second magnetic guide shoe 32, the mover 1 and the second stator magnetic arm 42. A third bias magnetic flux 123 is formed between the third permanent magnet 23, the third magnetic guide shoe 33, the mover 1 and the third stator magnetic arm 43. A fourth bias magnetic flux 124 is formed between the fourth permanent magnet 24, the fourth magnetic guide shoe 34, the mover 1 and the fourth stator magnetic arm 44.

[0052] In this embodiment, the mover 1 and the stator assembly (permanent magnet 2, magnetic guide shoe 3) that provide the bias magnetic field are spatially misaligned (i.e., not traditionally directly opposite each other). This ensures that when the mover 1 rotates at large angles around the X or Y axis, the vertical distance (i.e., the effective air gap length) between the mover 1 and the core working surface that generates the effective Maxwell force between them remains essentially constant or changes very little. This design decouples the range of motion from the air gap changes that cause nonlinearity, thereby allowing for large-angle motion without significantly sacrificing the linearity and accuracy of control.

[0053] In this embodiment, four sets of permanent magnets 2 and magnetic guide shoes 3 are evenly distributed around the mover 1, and together with four sets of stator magnetic arms 4, magnetic guide base 6, and magnetic guide column 7, they form a unified magnetic circuit system. The design of this magnetic circuit system enables a single mover 1 to respond to three independent current excitation modes simultaneously, thereby realizing integrated parallel drive of three degrees of freedom: rotation around the X-axis (θx), rotation around the Y-axis (θy), and translation along the Z-axis (Z), without the need for mechanical series connection of multiple actuators.

[0054] In this embodiment, chamfers can be provided around the mover 1, which helps to optimize the magnetic flux flow and increase the effective working area, thereby maximizing the generated torque or electromagnetic force. The specific shape and angle of the chamfers can be adjusted as needed. The sidewalls adjacent to the mover 1 and the magnetic shoe 3 are designed with chamfers at specific angles. The chamfer design around the mover 1 is not merely a manufacturing feature; its function is to guide the bias magnetic flux and control the magnetic flux to change direction more smoothly, increasing the effective working area between the magnetic flux and the mover 1, thereby maximizing the efficiency of electromagnetic torque and force output. It is a key structural design for optimizing magnetic circuit performance.

[0055] In this embodiment, the four sets of stator magnetic arms 4, the magnetic base 6, and the magnetic column 7 are all of separate structure for ease of processing. In other embodiments, they can also be manufactured using an integrated molding process.

[0056] In this embodiment, the connections between the permanent magnet 2 and the magnetic shoe 3, between the permanent magnet 2 and the stator arm 4, and between the stator arm 4 and the magnetic base 6 can all be fixed by adhesive bonding, or supplemented by mechanical positioning fasteners such as pins, clips, or bolts. To achieve a compact structure, adhesive bonding is preferred.

[0057] In this embodiment, the coil windings can be configured as a single group or multiple groups according to the actuator's shape and space requirements. An insulating layer, such as insulating varnish, insulating glue, plastic bushing, or ceramic layer, must be provided between the excitation coil 5 and the stator magnetic arm 4.

[0058] In this embodiment, the magnetically conductive components, such as the mover 1, stator magnetic shoe 3, stator magnetic arm 4, magnetically conductive base 6, and magnetically conductive column 7, are all made of soft magnetic materials with high saturation magnetic flux density and low loss, such as silicon steel sheets, iron-nickel alloys, soft magnetic composite materials (SMC), or iron-based amorphous alloys.

[0059] In this embodiment, the permanent magnet 2 can be made of neodymium iron boron (NdFeB). In other embodiments, the permanent magnet 2 can be made of high remanence materials such as ferrite.

[0060] In this embodiment, the flexible diaphragm 8 can be made of titanium alloy and designed as a fan-shaped or cross-shaped flexible hinge structure to provide the required support stiffness and freedom of movement.

[0061] This embodiment provides a control method for a Maxwell force-driven three-degree-of-freedom electromagnetic actuator: based on the above magnetic circuit structure, a current distribution method for four independent excitation coils 5 is proposed, and the three degrees of freedom are completely decoupled through three specific current excitation modes. It should be noted that in this embodiment, up, down, left and right refer to the directions shown in the figure.

[0062] θx mode: A pair of X-direction symmetrical excitation coils 5 are supplied with current in a specific direction, such as the first excitation coil 51 and the second excitation coil 52 being supplied with opposite and equal currents.

[0063] θy mode: A specific direction of current is passed through another pair of Y-axis symmetrical excitation coils 5, such as the third excitation coil 53 and the fourth excitation coil 54 being passed through opposite and equal currents.

[0064] Z mode: Current is passed through the four excitation coils 5 in a specific direction, such as the first excitation coil 51, the second excitation coil 52, the third excitation coil 53 and the fourth excitation coil 54, all in the same direction and of the same size.

[0065] like Figure 3 and Figure 7 As shown, the core magnetic circuit design features of this invention are as follows: the magnetization direction of the permanent magnet 2 is vertically upward, and the length of the magnetization path is slightly greater than the thickness of the mover 1. This allows the bias magnetic flux generated to originate from the N pole of the permanent magnet 2, change direction after passing through the magnetic guide shoe 3, be injected obliquely above the mover 1, and then flow out obliquely below the mover 1, entering the stator magnetic arm 4, and finally returning to the S pole of the permanent magnet 2, forming a closed loop. Through this design, the magnitude of the bias magnetic flux generated by the permanent magnet 2 is equal in the four main working air gaps (upper left, lower left, upper right, and lower right), but there is a specific symmetrical and anti-symmetrical relationship relative to the flow direction of the mover 1. For example, in Figure 3 In the X-axis view, the bias magnetic flux in the two upper air gaps (the first constant air gap 131 and the second constant air gap 132) flows into the mover 1, while the bias magnetic flux in the two lower air gaps (the first working air gap 141 and the second working air gap 142) flows out of the mover 1. Figure 4 Similarly, a similar symmetrical distribution can be formed along the Y-axis. This flow design is the physical basis for achieving decoupled three-degree-of-freedom drive.

[0066] In this embodiment, all four excitation coils 5 can be driven independently. When currents of different directions and magnitudes are applied, control magnetic fluxes 15 of different directions are generated in the stator magnetic arm 4. The control magnetic fluxes 15 and the aforementioned permanent magnet bias flux are linearly superimposed in the four working air gaps, and form a closed magnetic circuit through the mover 1, stator magnetic arm 4, magnetically conductive base 6, and magnetically conductive column 7, thereby generating the required Maxwell force or torque. The specific control mode is as follows:

[0067] like Figure 3 and Figure 7 As shown, the process of controlling rotation (θx) around the X-axis is as follows: when an excitation current in a specific direction (such as...) is applied to the first excitation coil 51 and the second excitation coil 52... Figure 3When the direction is reversed, an upward control flux 15 is generated in the first stator magnetic arm 41 on the left and a downward control flux 15 is generated in the second stator magnetic arm 42 on the right. The control flux 15 flows into the mover 1 from the lower left first working air gap 141 and flows out of the mover 1 from the lower right second working air gap 142. After superimposing with the first bias flux 121 and the second bias flux 122, the magnetic field in the lower left first working air gap 141 weakens and the magnetic field in the lower right second working air gap 142 strengthens. The electromagnetic force on the mover 1 on the lower left side decreases and the electromagnetic force on the lower right side increases, thereby generating a positive rotational torque around the X-axis. Reversing the current direction of the first excitation coil 51 and the second excitation coil 52 will generate a reverse torque.

[0068] like Figure 4 and Figure 8 As shown, the process of controlling rotation (θy) around the Y-axis is as follows: when an excitation current in a specific direction (such as...) is applied to the third excitation coil 53 and the fourth excitation coil 54... Figure 4 When the direction is reversed, an upward control flux 15 is generated in the third stator magnetic arm 43 on the left and a downward control flux 15 is generated in the fourth stator magnetic arm 44 on the right. The control flux 15 flows into the mover 1 from the lower left third working air gap 143 and flows out of the mover 1 from the lower right fourth working air gap 144. After superimposing with the third bias flux 123 and the fourth bias flux 124, the magnetic field in the lower left third working air gap 143 weakens and the magnetic field in the lower right fourth working air gap 144 strengthens. The electromagnetic force on the mover 1 decreases on the lower left and increases on the lower right, thereby generating a rotational torque around the Y-axis. Reversing the current direction of the third excitation coil 53 and the fourth excitation coil 54 reverses the torque.

[0069] like Figure 5 , Figure 6 , Figure 9 and Figure 10 As shown, the process of translational (Z) control along the Z-axis is as follows: a current in a specific direction (e.g., current is applied to the first excitation coil 51 and the second excitation coil 52) Figure 5 When a specific direction current is applied to both the third excitation coil 53 and the fourth excitation coil 54 (e.g., in the direction of the center), the current in a specific direction is applied simultaneously (e.g., in the direction of the center). Figure 6In the first stator arm 41, second stator arm 42, third stator arm 43, and fourth stator arm 44, an upward-directed control magnetic flux 15 is generated. This control magnetic flux 15 flows into the mover 1 from the lower periphery and exits from the central region of the mover 1 into the magnetically conductive column 7. After superimposing with the first bias magnetic flux 121, second bias magnetic flux 122, third bias magnetic flux 123, and fourth bias magnetic flux 124, the total magnetic flux (or magnetic field strength) within the first working air gap 141, second working air gap 142, third working air gap 143, and fourth working air gap 144 is uniformly weakened. Therefore, the electromagnetic force on the lower periphery of the mover 1 decreases, while the electromagnetic force on the upper periphery remains unchanged, resulting in a net electromagnetic resultant force upward along the Z-axis. Reversing the current direction of all excitation coils 5 generates a downward resultant force.

[0070] As can be seen, when the current in all excitation coils 5 is zero, there are only bias magnetic fluxes of equal magnitude in each air gap, and the resultant force and resultant torque of the electromagnetic force on the mover 1 are both zero, and it is in equilibrium.

[0071] In this embodiment, key designs such as the "three-degree-of-freedom integrated magnetic circuit topology" and the "misaligned moving-stator configuration" solve the technical problems of structural redundancy, lack of degrees of freedom, contradiction between motion range and linear drive, and control coupling in existing electromagnetic actuators. Specifically, because four sets of magnetic circuits share a single mover 1 and the magnetic flux flow direction is specially designed, a single stator system can respond to three independent current modes, thus naturally realizing three-degree-of-freedom parallel drive in physical structure, achieving high integration and compactness. At the same time, due to the misaligned arrangement of the mover 1, the magnetic shoe 3, and the stator magnetic arm 4, the effective working air gap length is basically constant when rotating around the X / Y axis, thereby decoupling the large-angle deflection motion from the air gap change that causes strong nonlinearity, achieving a unity of large motion range and high control linearity. In addition, the specially set magnetic column 7 provides an efficient magnetic circuit for Z-axis translation, while the symmetrical current excitation mode corresponds to the generation of nearly decoupled force and torque output. Ultimately, these features together enable the electromagnetic actuator of the present invention to achieve a wide range, high precision, and independently controllable motion along the three axes of θx, θy, and Z within a compact unit.

[0072] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A Maxwell force-driven three-degree-of-freedom electromagnetic actuator, characterized in that, include: The four sets of permanent magnets (2) are evenly distributed around the four sides of the mover (1), and the upper N pole of each set of permanent magnets (2) is connected to a magnetic shoe (3), and the lower S pole of each set of permanent magnets (2) is connected to the top of a stator magnetic arm (4). The magnetic shoe (3) is located diagonally above the side wall of the mover (1), and the stator magnetic arm (4) is located diagonally below the side wall of the mover (1), so that the rotation center of the mover (1) is located in the middle plane of the permanent magnet (2). Each stator magnetic arm (4) is independently wound with an excitation coil (5), and the bottom end of the stator magnetic arm (4) is connected to the magnetic base (6), the magnetic column (7), and the flexible diaphragm (8). The magnetic base (6) is connected to the mounting groove (601); the middle part of the magnetic base (6) is connected to the vertically arranged magnetic column (7), the top of the magnetic column (7) extends to the Z-direction center plane of the internal cavity of the mover (1) and is fixed to the middle part of the flexible diaphragm (8); the edge of the flexible diaphragm (8) is connected to the mounting boss (101) in the internal cavity of the mover (1); the four sets of permanent magnets (2), magnetic shoes (3), four stator magnetic arms (4), magnetic base (6) and magnetic column (7) together constitute a magnetic circuit system so that the mover (1) can respond to three independent current excitation modes at the same time, thereby realizing the integrated parallel drive of three degrees of freedom: rotation around the X-axis (θx), rotation around the Y-axis (θy) and translation along the Z-axis (Z).

2. The Maxwell force-driven three-degree-of-freedom electromagnetic actuator according to claim 1, characterized in that, The moving part (1) has chamfers on all four sides.

3. The Maxwell force-driven three-degree-of-freedom electromagnetic actuator according to claim 1, characterized in that, The excitation coils (5) on the four stator magnetic arms (4) can be driven independently, and an insulation layer is provided between the excitation coils (5) and the stator magnetic arms (4).

4. The Maxwell force-driven three-degree-of-freedom electromagnetic actuator according to claim 1, characterized in that, The stator magnetic arm (4) adopts a split structure or an integrated molding structure; the magnetic base (6) adopts a split structure or an integrated molding structure; the magnetic column (7) adopts a split structure or an integrated molding structure.

5. The Maxwell force-driven three-degree-of-freedom electromagnetic actuator according to any one of claims 1 to 4, characterized in that, The mover (1), magnetic shoe (3), stator arm (4), magnetic base (6) and magnetic column (7) are all made of soft magnetic material; the permanent magnet (2) is made of neodymium iron boron or ferrite material; the flexible diaphragm (8) is made of titanium alloy material.

6. The Maxwell force-driven three-degree-of-freedom electromagnetic actuator according to any one of claims 1 to 4, characterized in that, The permanent magnet (2) is bonded to the magnetic shoe (3), the permanent magnet (2) is bonded to the stator arm (4), and the stator arm (4) is bonded to the magnetic base (6).

7. The Maxwell force-driven three-degree-of-freedom electromagnetic actuator according to any one of claims 1 to 4, characterized in that, The permanent magnet (2) includes a first permanent magnet (21), a second permanent magnet (22), a third permanent magnet (23) and a fourth permanent magnet (24), and the magnetic shoe (3) includes a first magnetic shoe (31), a second magnetic shoe (32), a third magnetic shoe (33) and a fourth magnetic shoe (34). The stator magnetic arm (4) includes a first stator magnetic arm (41), a second stator magnetic arm (42), a third stator magnetic arm (43) and a fourth stator magnetic arm (44) that are evenly distributed around the outer periphery of the mover (1). A first excitation coil (51) is wound on the first stator magnetic arm (41), a second excitation coil (52) is wound on the second stator magnetic arm (42), a third excitation coil (53) is wound on the third stator magnetic arm (43), and a fourth excitation coil (54) is wound on the fourth stator magnetic arm (44). There are constant air gaps between the upper part of the outer wall of the mover (1) and the permanent magnet (2) and the magnetic shoe (3), and between the mover (1) and the magnetic column (7). There are working air gaps between the lower part of the outer wall of the mover (1) and the permanent magnet (2) and the stator arm (4). The magnetization direction of the permanent magnet (2) is vertically upward. A first bias magnetic flux (121) is formed between the first permanent magnet (21), the first magnetic guide shoe (31), the mover (1) and the first stator magnetic arm (41). A second bias magnetic flux (122) is formed between the second permanent magnet (22), the second magnetic guide shoe (32), the mover (1) and the second stator magnetic arm (42). A third bias magnetic flux (123) is formed between the third permanent magnet (23), the third magnetic guide shoe (33), the mover (1) and the third stator magnetic arm (43). A fourth bias magnetic flux (124) is formed between the fourth permanent magnet (24), the fourth magnetic guide shoe (34), the mover (1) and the fourth stator magnetic arm (44).

8. A control method applicable to the Maxwell force-driven three-degree-of-freedom electromagnetic actuator as described in claim 7, characterized in that, The control of the three-degree-of-freedom electromagnetic actuator includes rotation control around the X-axis (θx): when an excitation current in a preset direction is applied to the first excitation coil (51) and the second excitation coil (52), an upward control flux (15) is generated in the first stator magnetic arm (41), and a downward control flux (15) is generated in the second stator magnetic arm (42); the control flux (15) flows into the mover (1) from the first working air gap (141) between the mover (1) and the first stator magnetic arm (41), and the driven mover (1)... The mover (1) flows out of the second working air gap (142) between the first stator magnetic arm (42) and the second stator magnetic arm (42), and after being superimposed with the first bias magnetic flux (121) and the second bias magnetic flux (122), the magnetic field of the first working air gap (141) is weakened and the magnetic field in the second working air gap (142) is strengthened; the electromagnetic force on the mover (1) on the side of the first stator magnetic arm (41) decreases and the electromagnetic force on the side of the second stator magnetic arm (42) increases, thereby generating a positive rotational torque around the X-axis.

9. The control method according to claim 8, characterized in that, The control of the three-degree-of-freedom electromagnetic actuator also includes rotation (θy) control around the Y-axis: when an excitation current in a preset direction is applied to the third excitation coil (53) and the fourth excitation coil (54), an upward control flux (15) is generated in the third stator magnetic arm (43) and a downward control flux (15) is generated in the fourth stator magnetic arm (44); the control flux (15) flows into the mover (1) from the third working air gap (143) and flows out of the mover (1) from the fourth working air gap (144), and after being superimposed with the third bias flux (123) and the fourth bias flux (124), the magnetic field in the third working air gap (143) is weakened and the magnetic field in the fourth working air gap (144) is strengthened; the electromagnetic force on the mover (1) on the side of the third stator magnetic arm (43) decreases and the electromagnetic force on the side of the fourth stator magnetic arm (44) increases, thereby generating a positive rotational torque around the Y-axis.

10. The control method according to claim 8, characterized in that, The control of the three-degree-of-freedom electromagnetic actuator also includes translational (Z) control along the Z-axis: when a preset direction current is applied to the first excitation coil (51) and the second excitation coil (52), and a preset direction current is also applied to the third excitation coil (53) and the fourth excitation coil (54), an upward control magnetic flux (15) is generated in the first stator magnetic arm (41), the second stator magnetic arm (42), the third stator magnetic arm (43) and the fourth stator magnetic arm (44); the control magnetic flux (15) flows into the mover (1) from the bottom around the four sides, flows out from the middle area of ​​the mover (1), and enters the magnetic column (7). After being superimposed with the first bias magnetic flux (121), the second bias magnetic flux (122), the third bias magnetic flux (123) and the fourth bias magnetic flux (124), the magnetic field in all working air gaps is uniformly weakened; the electromagnetic force on the lower side of the mover (1) is reduced, while the electromagnetic force on the upper side remains unchanged, thereby generating a net electromagnetic resultant force along the Z-axis.

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