A magnetic suspension gimbal tilt variable speed flywheel with piezoelectric actuation error compensation

Abstract

The application discloses a magnetic suspension universal support tilting variable-speed flywheel with piezoelectric actuation error compensation and relates to the technical field of micro spacecraft attitude control. The application adopts the above-mentioned magnetic suspension universal support tilting variable-speed flywheel with piezoelectric actuation error compensation, an embedded ring-shaped piezoelectric actuation device and a permanent magnet biased magnetic suspension universal joint are embedded in a compact space, the embedded ring-shaped piezoelectric actuation device compensates the rotation error of the rotor of the tilting variable-speed flywheel, the zero tilting stiffness and zero damping characteristics of the permanent magnet biased magnetic suspension universal joint are matched, and the pointing accuracy of the tilting variable-speed flywheel is improved.

Description

A piezoelectrically actuated error-compensated magnetically levitated universal support tilting variable speed flywheel Technical Field

[0001] This invention relates to the field of attitude control technology for micro spacecraft, and in particular to a magnetically levitated universal support tilting variable speed flywheel with piezoelectric actuation error compensation. Background Technology

[0002] In recent years, micro-spacecraft have become a hot topic in spacecraft research due to their advantages of light weight, small size, and low cost. Lightweight design, integration, low cost, and good attitude control performance are urgent requirements for the development of micro-spacecraft technology. The attitude control system is the core subsystem of a micro-spacecraft and a major factor affecting its size, weight, and cost. Currently, momentum exchange-based attitude control is widely used in micro-spacecraft. The tilt-variable-speed flywheel, which integrates attitude measurement and momentum exchange-based attitude adjustment, has significant application value in micro-satellites and other spacecraft.

[0003] The tilting variable-speed flywheel utilizes the torque generated by the torque converter coil to control the flywheel's two-dimensional tilting motion, thereby changing the rotor's angular momentum amplitude and orientation to achieve three-degree-of-freedom momentum exchange. Conventional tilting variable-speed flywheels suffer from a certain degree of directional deviation due to structural limitations. Unlike traditional rotors, the tilting variable-speed flywheel's rotor resembles a cantilever support capable of two-dimensional tilting. Its directional deviation is a mixture of rotor rotational error and multi-frequency vibrations caused by dynamic imbalance within the rotor body during the tilting process. Currently, the most mature solution is to improve its directional deviation through machining and assembly, but this faces technical bottlenecks.

[0004] When a tilting variable-speed flywheel is used as an attitude measurement device, in order to reduce the influence of carrier attitude changes and torques outside the torque generator, the motion and torque coupling link between the rotor and the flywheel must have zero tilting stiffness and zero frictional damping. Existing flexible mechanical support schemes are difficult to guarantee high-precision stability, and traditional universal support schemes have large tilting stiffness and frictional damping, which also affect the identification and correction of rotor dynamic imbalance.

[0005] Since machining and assembly processes often struggle to reduce the pointing deviation of tilting variable-speed flywheels, this invention proposes a piezoelectric actuation-based active compensation mechanism. Piezoelectric actuators offer advantages such as high precision, fast response, large load capacity, and resistance to electromagnetic interference, thus meeting the error compensation requirements of tilting variable-speed flywheels. Currently, in other fields, piezoelectric actuators used for error compensation or vibration suppression research primarily employ piezoelectric stacks, arranging two or more stacks in a separated configuration to synthesize a specified trajectory within a plane. However, this solution is not advantageous in the research of micro-spacecraft where size and weight are critical constraints. Summary of the Invention

[0006] The purpose of this invention is to provide a piezoelectrically actuated error-compensated magnetically levitated universal support tilting variable speed flywheel. It uses a magnetically levitated coupling support to replace the traditional universal joint support device, achieving zero tilting stiffness and zero frictional damping. It uses a piezoelectric actuator as an active compensation mechanism to improve its pointing accuracy through an active error compensation mechanism.

[0007] To achieve the above objectives, the present invention provides a piezoelectrically actuated error-compensated magnetically levitated universal support tilting variable speed flywheel, including a tilt angle sensor assembly and a rotary transformer. The upper part of the rotary transformer is connected to a base. A bearing housing assembly and a motor assembly are disposed inside the base. The motor output shaft of the motor assembly is connected to a magnetically levitated universal joint. The magnetically levitated universal joint is fixedly connected to a rotor assembly. The upper part of the rotor assembly is fixedly connected to the tilt angle sensor. The rotor assembly is disposed inside the base shown.

[0008] Preferably, the torque generator stator is fixedly connected to the base, and the base is connected to the bearing housing assembly by bolts. The bearing housing assembly includes a bearing housing, a bearing end cover, and an annular piezoelectric sheet. The upper end of the annular piezoelectric sheet is connected to the bearing end cover through a piezoelectric sheet locking flange, the bottom of the annular piezoelectric sheet is connected to the bearing housing, and the lower part of the bearing housing is connected to the bearing end cover.

[0009] Preferably, the bearing end cover is connected to a locking nut, the inside of the locking nut is connected to the motor output shaft, and the lower part of the motor output shaft is connected to the second locking nut.

[0010] Preferably, multiple annular piezoelectric sheets are provided, and the multiple annular piezoelectric sheets are connected in series. The annular piezoelectric sheets are divided into PZT-A and PZT-B. After applying an electric field, they can generate deformation in the X-axis and Y-axis directions, respectively, and their strain is:

[0011] ;

[0012] ;

[0013] In the formula: - Strain in the corresponding direction of the piezoelectric element; E - Electric field strength; - Piezoelectric constant; U - Voltage applied to the piezoelectric element; t - Piezoelectric element thickness.

[0014] Preferably, the bearing housing is provided with a deep groove ball bearing, and multiple deep groove ball bearings are provided. The interior of the multiple deep groove ball bearings is connected to the motor output shaft, and the upper part of the motor output shaft is fixedly connected to the lower flange of the magnetic levitation universal joint.

[0015] Preferably, the magnetic levitation universal joint includes a cross coupling and a biased permanent magnet bearing. A universal joint deep groove ball bearing is disposed outside the biased permanent magnet bearing. Multiple universal joint deep groove ball bearings and multiple biased permanent magnet bearings are disposed. Multiple biased permanent magnet bearings and universal joint deep groove ball bearings are connected to the cross coupling. The end of the cross coupling is connected to the bearing end cap.

[0016] Preferably, the plurality of the opposite polarity permanent magnet bias bearings and the universal joint deep groove ball bearings are all connected to the universal joint bearing housing. The lower part of the universal joint bearing housing is provided with the lower flange, and the upper flange is correspondingly provided with the lower flange. The upper flange is fixedly connected to the rotor assembly.

[0017] Preferably, the motor output shaft is connected to the motor rotor, the motor rotor is provided with a motor stator, the lower part of the motor stator is connected to the motor cover, and the lower part of the motor cover is connected to the rotary transformer.

[0018] Therefore, this invention employs a piezoelectric actuation error compensation magnetic levitation universal support tilting variable speed flywheel. By using an embedded annular piezoelectric actuation device, it effectively compensates for the rotational error of the tilting variable speed flywheel rotor while ensuring lightweight and integrated design. Furthermore, the use of a permanent magnet biased magnetic levitation universal joint effectively reduces the complexity of the piezoelectric braking control scheme. Ultimately, this achieves low-cost, high-precision, and reliable tilting variable speed flywheel control. This invention has a simple structure and is easy to promote and use.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 is a schematic diagram of an embodiment of a magnetically levitated universal support tilting speed-changing flywheel with piezoelectric actuation error compensation according to the present invention.

[0021] Figure 2 is an exploded view of a magnetically levitated universal support tilting speed-changing flywheel with piezoelectric actuation error compensation according to the present invention.

[0022] Figure 3 is a cross-sectional view of a magnetically levitated universal support tilting speed-changing flywheel with piezoelectric actuation error compensation according to the present invention;

[0023] Figure 4 is a schematic diagram of the structure of the magnetic levitation universal joint of the present invention;

[0024] Figure 5 is a cross-sectional view of the magnetic levitation universal joint of the present invention;

[0025] Figure 6 is a schematic diagram of the structure of the opposite polarity permanent magnet biased magnetic levitation bearing of the present invention;

[0026] Figure 7 is a schematic diagram of the bearing housing assembly structure of the present invention;

[0027] Figure 8 is a cross-sectional view of the bearing housing assembly of the present invention;

[0028] Figure 9 is a schematic diagram of the annular piezoelectric sheet of the present invention;

[0029] Figure 10 is a simplified diagram of the connection structure between the annular piezoelectric sheet and the rotor assembly of the present invention.

[0030] Figure Labels

[0031] 1. Swing angle sensor assembly; 2. Rotor assembly; 3. Magnetic levitation universal joint; 4. Motor output shaft; 5. Bearing housing assembly; 6. Motor assembly; 7. Torque generator stator; 8. Base; 9. Universal joint deep groove ball bearing; 10. Opposite polarity permanent magnet bias bearing; 11. Universal joint bearing housing; 12. Cross coupling; 13. Upper flange; 14. Lower flange; 15. Bearing end cover; 16. Piezoelectric locking flange; 17. Annular piezoelectric element; 18. Bearing housing; 19. Deep groove ball bearing; 20. Rotary transformer; 21. Locking nut; 22. Locking nut II; 23. Motor rotor; 24. Motor stator; 25. Motor cover. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0034] Example

[0035] Please refer to Figures 1-10. This invention provides a piezoelectric actuation error compensation magnetic levitation universal support tilting variable speed flywheel, including a tilt angle sensor assembly 1 and a rotary transformer 20. The upper part of the rotary transformer 20 is connected to a base 8. A bearing housing assembly 5 and a motor assembly 6 are disposed within the base 8. The bearing housing assembly 5 is a shaft support structure for the motor output shaft. The motor output shaft 4 of the motor assembly 6 is connected to a magnetic levitation universal joint 3. The magnetic levitation universal joint 3 is fixedly connected to a rotor assembly 2. The magnetic levitation universal joint 3 is fixedly connected to the rotor assembly 2 via an upper flange 13 and to the motor output shaft 4 via a lower flange 14, responsible for providing the rotor with two tilting degrees of freedom and the rotor rotational degree of freedom. The bearing housing assembly 5, while serving as a shaft support structure for the motor output shaft 4, also embeds an annular piezoelectric actuator as an active compensation mechanism. The tilt angle sensor assembly 1 is fixedly connected above the rotor assembly 2, responsible for rotor tilt angle detection. The torque stator 7 is fixedly connected to the base and sandwiched between the inner and outer magnets of the torque generator in the rotor assembly. The torque converter consists of a flywheel rotor assembly (torque converter magnets and a yoke) and a torque converter stator. The flywheel rotor assembly, part of the torque converter, provides a changing magnetic field. The energized coils carried by the torque converter stator generate a Lorentz force in the changing magnetic field. The torque converter stator 7 is used to achieve tilting motion; its principle will not be explained here.

[0036] The torque generator stator 7, rotor assembly 2, bearing housing assembly 5, and motor assembly 6 are all housed within a base 8. The base 8 is connected to the bearing housing assembly 5 by bolts. The bearing housing assembly 5 includes a bearing housing 18, a bearing end cover 15, and an annular piezoelectric plate 17. The upper end of the annular piezoelectric plate 17 is connected to the bearing end cover 15 via a piezoelectric plate locking flange 16. The bottom of the annular piezoelectric plate 17 is connected to the bearing housing 18, and the lower part of the bearing housing 18 is connected to the bearing end cover 15. The bearing end cover 15 is connected to a locking nut 21. The interior of the locking nut 21 is connected to the motor output shaft 4, and the lower part of the motor output shaft 4 is connected to a second locking nut 22.

[0037] Multiple annular piezoelectric elements 17 are arranged in series. The countersunk screws connecting the bearing end cap 15 of the bearing housing assembly 5 and the piezoelectric element locking flange 16 provide axial pressure, pre-tightening the multiple annular piezoelectric elements 17 to ensure their series operation and amplify the stroke. The annular piezoelectric elements 17 are divided into four different polarization regions, which can be classified into pairs as PZT-A and PZT-B. As shown in Figure 9, "+" indicates that the piezoelectric polarization direction is from outside the paper to the paper surface, and "-" indicates the opposite. When an electric field E as shown in Figure 9 is applied to the annular piezoelectric element 17, due to the inverse piezoelectric effect, the annular piezoelectric element 17 will deform as shown in Figure 9. Taking PZT-A as an example, the left region elongates, and the right region shortens, causing the entire annular piezoelectric element to rotate along the y-axis. Its elongation is the same as its compression, and the strain in the corresponding direction is:

[0038] ;

[0039] ;

[0040] In the formula: - Strain in the corresponding direction of the piezoelectric element; E - Electric field strength; - Piezoelectric constant; U - Voltage applied to the piezoelectric element; t - Piezoelectric element thickness.

[0041] Because the top of the annular piezoelectric sheet 17 is pressed tightly and the bottom is fixed to the bearing seat 18 of the bearing seat assembly 5, a force is generated on the entire bearing seat assembly 5 and the rotor assembly 2. As shown in Figure 10, when the simplified mechanical connection structure between the annular piezoelectric sheet 17 and the rotor assembly 2 is a rigid connection, the strain of PZT-A and PZT-B under the inverse piezoelectric effect will be transmitted to the rotor assembly 2, corresponding to the displacement of the x-axis and y-axis in the rotor cross-section, respectively. During the active error compensation task, the rotational error of the rotor on the cross-section is obtained. After that, the corresponding calculation can be obtained. E and U complete the active error compensation task.

[0042] The bearing housing 18 is equipped with a deep groove ball bearing 19. The deep groove ball bearing 19 is arranged vertically, and multiple deep groove ball bearings 19 are arranged. The internal parts of the multiple deep groove ball bearings 19 are connected to the motor output shaft 4. The motor output shaft 4 passes through the bearing housing assembly 5, and the upper part of the motor output shaft 4 is fixedly connected to the lower flange 14 of the magnetic levitation universal joint 3.

[0043] The magnetic levitation universal joint 3 includes a cross coupling 12 and a biased permanent magnet bearing 10. A universal joint deep groove ball bearing 9 is disposed outside the biased permanent magnet bearing 10. Multiple deep groove ball bearings 9 and multiple biased permanent magnet bearings 10 are provided. All multiple biased permanent magnet bearings 10 and universal joint deep groove ball bearings 9 are connected to the cross coupling 12. The deep groove ball bearings 9 are disposed outside the biased permanent magnet bearings 10. The end of the cross coupling 12 is connected to a bearing end cover 15. All multiple biased permanent magnet bearings 10 and universal joint deep groove ball bearings 9 are connected to a universal joint bearing housing 11. A lower flange 14 is disposed at the lower part of the universal joint bearing housing 11.

[0044] When the magnetic levitation bearing is working, it generates radial levitation force, as shown in Figure 6, which counteracts the weight of the universal joint. There is no mechanical contact between the stator (opposite polarity permanent magnet bias magnetic bearing 10) and the rotor (cross coupling 12), realizing two-dimensional tilting with zero tilting stiffness and zero frictional damping of the tilting variable speed flywheel.

[0045] The motor output shaft 4 is connected to the motor rotor 23. The motor rotor 23 is equipped with a motor stator 24. The side end of the motor stator 24 is connected to the base 8. The lower part of the motor stator 24 is connected to the motor cover 25. The lower part of the motor cover 25 is connected to the rotary transformer 20.

[0046] Therefore, this invention employs a piezoelectric actuation error compensation magnetic levitation universal support tilting variable speed flywheel. By using an embedded annular piezoelectric actuation device, it effectively compensates for the rotational error of the tilting variable speed flywheel rotor while ensuring lightweight and integrated design. Furthermore, the use of a permanent magnet biased magnetic levitation universal joint effectively reduces the complexity of the piezoelectric braking control scheme. Ultimately, this achieves low-cost, high-precision, and reliable tilting variable speed flywheel control. This invention has a simple structure and is easy to promote and use.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A piezoelectrically actuated error-compensated magnetically levitated universal support tilting variable speed flywheel, characterized in that: The system includes a swing angle sensor assembly and a rotary transformer. The upper part of the rotary transformer is connected to a base. A bearing housing assembly and a motor assembly are housed within the base. The motor output shaft of the motor assembly is connected to a magnetic levitation universal joint, which is fixedly connected to a rotor assembly. The upper part of the rotor assembly is fixedly connected to the swing angle sensor. The rotor assembly is disposed inside the base. A torque converter stator is fixedly connected to the base. The base is connected to the bearing housing assembly by bolts. The bearing housing assembly includes a bearing housing, a bearing end cap, and an annular piezoelectric plate. The upper end of the piezoelectric sheet is connected to the bearing end cover via a piezoelectric sheet locking flange. The bottom of the annular piezoelectric sheet is connected to the bearing seat, and the lower part of the bearing seat is connected to the bearing end cover. The bearing end cover is connected to a locking nut, the inside of which is connected to the motor output shaft, and the lower part of the motor output shaft is connected to the locking nut. Multiple annular piezoelectric sheets are connected in series. These annular piezoelectric sheets are classified as PZT-A and PZT-B. When an electric field is applied, they can generate deformations in the X-axis and Y-axis directions, respectively, with strains as follows: ； In the formula: - Strain in the corresponding direction of the piezoelectric element; E - Electric field strength; - Piezoelectric constant; U - Voltage applied to the piezoelectric element; t - Piezoelectric element thickness.

2. The piezoelectric actuation error compensation magnetic levitation universal support tilting variable speed flywheel according to claim 1, characterized in that: The bearing housing is equipped with multiple deep groove ball bearings. The interior of each deep groove ball bearing is connected to the motor output shaft. The upper part of the motor output shaft is fixedly connected to the lower flange of the magnetic levitation universal joint.

3. The piezoelectric actuation error compensation magnetic levitation universal support tilting speed-changing flywheel according to claim 2, characterized in that: The magnetic levitation universal joint includes a cross coupling and a permanent magnet bias bearing of opposite polarity. A universal joint deep groove ball bearing is provided on the outside of the permanent magnet bias bearing of opposite polarity. Multiple universal joint deep groove ball bearings and multiple permanent magnet bias bearings of opposite polarity are provided. Multiple permanent magnet bias bearings of opposite polarity and universal joint deep groove ball bearings are connected to the cross coupling. The end of the cross coupling is connected to the bearing end cover.

4. The piezoelectric actuation error compensation magnetic levitation universal support tilting speed-changing flywheel according to claim 3, characterized in that: Multiple opposite polarity permanent magnet bias bearings and universal joint deep groove ball bearings are connected to universal joint bearing housings. The lower part of the universal joint bearing housing is provided with the lower flange, and the upper flange is correspondingly provided with the lower flange. The upper flange is fixedly connected to the rotor assembly.

5. A piezoelectric actuation error compensation magnetic levitation universal support tilting speed-changing flywheel according to claim 4, characterized in that: The motor output shaft is connected to the motor rotor, and a motor stator is provided outside the motor rotor. The lower part of the motor stator is connected to the motor cover, and the lower part of the motor cover is connected to the rotary transformer.

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