Active magnetic levitation long-stroke vibration isolation pointing actuator and active control method

Abstract

This invention discloses an active magnetic levitation long-stroke vibration isolation pointing actuator and its active control method. The actuator's coil is fixed to the flange of the central rod, and the magnet is fixedly connected to the central support plate of the outer shell, with the coil and magnet coaxial. The front-end lateral force-bearing component and the rear-end lateral force-bearing component are coaxially connected through the central rod. A spring is sleeved on the outside of the central rod, with its two ends fixed to the central support plate of the outer shell and the rear-end lateral force-bearing component, respectively, providing axial stiffness and maintaining zero-position stability. Electromagnets are divided into two groups, arranged around the front-end and rear-end lateral force-bearing components, respectively. Eddy current sensors detect the radial deflection of the output rod in real time. An active control algorithm adjusts the current of each electromagnet to generate a controllable attractive force that constrains the output rod to the axial position, achieving contactless and frictionless radial support. Under the active control method, this invention can achieve vibration isolation pointing with a large stroke of 25mm and micron-level accuracy, and the radial stiffness can be dynamically adjusted as needed.

Description

Technical Field

[0001] This invention relates to the field of active drive control technology for magnetic levitation, specifically to an active magnetic levitation long-stroke vibration isolation pointing actuator and active control method. Background Technology

[0002] Space optical payloads and precision measuring instruments place extremely high demands on the stability and pointing accuracy of the operating platform. As a key component for vibration isolation and pointing, the actuator must simultaneously possess characteristics such as large stroke, high precision, frictionless operation, and long lifespan. Traditional electromagnetic actuators often use springs to radially constrain the central rod, but the limited deformation capacity of the springs results in a small actuation stroke, failing to meet the needs of wide-range pointing. While ball screw actuators can achieve large strokes, they suffer from rigid contact, wear, and poor high-frequency response. Hydraulic actuators, on the other hand, suffer from severe response lag. The defect is 100ms.

[0003] In recent years, magnetic levitation technology has attracted attention due to its advantages of being contactless and wear-free. Publicly available permanent magnet levitation schemes utilize the principle of like poles repulsion in permanent magnets to provide radial constraint. While this avoids friction, the constraint force is fixed and cannot be adjusted, and it is difficult to suppress yaw under complex disturbances, thus limiting directional accuracy. Therefore, developing an actuator that can achieve a large stroke, actively suppress yaw, and has adjustable stiffness has significant application value. Summary of the Invention

[0004] To address the problems of limited stroke, friction loss, and complex control in existing actuators, the present invention aims to provide an active magnetic levitation long-stroke vibration isolation pointing actuator and an active control method. Through the design of magnetic levitation constraint and spring force balance, a large-stroke precision vibration isolation pointing with controllable axial force is achieved.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An active magnetic levitation long-stroke vibration isolation directional actuator includes a housing 1, a sleeve 2, a sleeve connector 3, a front transverse force-bearing component 4, an eddy current sensor connector 5, an eddy current sensor 6, an air gap protection component 7, an electromagnet 8, a central rod 9, a coil 10, a magnet 11, a spring 12, a spring retaining ring 13, a rear transverse force-bearing component 14, and a base 15. The output rod 16 is composed of the sleeve 2, sleeve connector 3, front transverse force-bearing component 4, center rod 9, coil 10, spring retaining ring 13, and rear transverse force-bearing component 14.

[0006] The coil 10 is fixed to the flange of the central rod 9, and the magnet 11 is fixed to the central support plate of the outer shell 1. The coil 10 and the magnet 11 are coaxial, forming a Lorentz force axial drive unit. The eddy current sensor connector 5, the air gap protection component 7, and the electromagnet 8 are fixed at the corresponding screw holes of the outer shell 1. The eddy current sensor 6 is fixed to the eddy current sensor connector 5 and is used to detect the radial displacement and yaw of the output rod 16 in real time. The front transverse force-bearing component 4 and the rear transverse force-bearing component 14 are respectively fixedly connected to the two ends of the central rod 9. There are multiple electromagnets 8, divided into front and rear groups. Each group of multiple electromagnets is centrally symmetrically installed on the outer shell 1, respectively opposite to the front transverse force-bearing component 4 and the rear transverse force-bearing component 14, forming a radial active magnetic levitation constraint. The spring 12 is sleeved on the outside of the central rod 9. One end of the spring is fixed to the central support plate of the outer shell 1 by the spring retaining ring 13, and the other end is fixed to the rear transverse force-bearing member 14 by the spring retaining ring 13. It is used to provide axial stiffness and maintain the axial zero position of the output rod 16. When the output rod 16 is radially offset by axial drive or external disturbance, the eddy current sensor 6 transmits the detection signal to the host computer. The host computer calculates the compensation current required by each electromagnet 8 according to the active control algorithm, and adjusts the attraction force of the electromagnet on the front transverse force-bearing member 4 and the rear transverse force-bearing member 14 so that the output rod 16 always stays in the axial position and realizes non-contact radial constraint. The spring 12 provides axial restoring force so that the output rod 16 returns to the zero position when there is no axial drive.

[0007] By adjusting the current in the electromagnet 8, the equivalent radial stiffness between the actuator output rod 16 and the housing 1 can be dynamically adjusted; by replacing the spring 12 with a different stiffness, the axial stiffness can be adjusted.

[0008] Preferably, the front transverse force-bearing component 4 and the rear transverse force-bearing component 14 are made of electrical pure iron or high magnetic permeability material to enhance electromagnetic attraction.

[0009] Preferably, the spring 12 is a helical spring, with its two ends clamped by the central support plate of the outer shell 1 and the spring fixing ring 13, and the rear transverse force-bearing member 14 and the spring fixing ring 13, respectively, so that the spring 12 is always in a compressed or stretched state, providing stable axial stiffness and a certain torsional stiffness; when the coil 10 is not energized, the actuator relies on the spring 12 to achieve passive vibration isolation.

[0010] Preferably, an air gap is formed between the front transverse force-bearing member 4 and the corresponding electromagnet 8; an air gap is also formed between the rear transverse force-bearing member 14 and the corresponding electromagnet 8; the air gap protection member 7 maintains a uniform gap with the front transverse force-bearing member 4 and the rear transverse force-bearing member 14 to prevent accidental collisions.

[0011] More preferably, an air gap of 0.5 mm is formed between the front transverse force-bearing member 4 and the corresponding four electromagnets 8; an air gap of 0.5 mm is also formed between the rear transverse force-bearing member 14 and the corresponding four electromagnets 8; and a uniform gap of 0.4 mm is maintained between the air gap protection member 7 and the front transverse force-bearing member 4 and the rear transverse force-bearing member 14 to prevent accidental collisions.

[0012] Preferably, there are eight electromagnets 8 in total, divided into two groups, front and back, with four in each group symmetrically mounted on the outer casing 1.

[0013] When no current is applied to coil 10, the preload of spring 12 keeps output rod 16 in an axial equilibrium position.

[0014] The active control method of the active magnetic levitation large-stroke vibration isolation pointing actuator involves applying equal bias currents to multiple electromagnets 8, causing the front transverse force-bearing component 4 and the rear transverse force-bearing component 14 to experience symmetrical initial attractive forces, resulting in the output rod 16 suspending near the central axis. Displacement or attitude data of the load mounted on the sleeve 2 is acquired through external sensors, and a driving current for the coil 10 is generated according to the pointing control requirements. The interaction between the magnet 11 and the coil 10 generates an axial Lorentz force, driving the output rod 16 to move axially, achieving a large-stroke displacement. The method also utilizes an eddy current sensor 6 to implement... The radial sway and deflection angle of the output rod 16 are monitored in real time, and the signals are fed back to the host computer. The host computer calculates the adjustment current of the electromagnet 8 required to suppress the sway according to the preset active control algorithm (such as PID control algorithm, sliding mode control algorithm, etc.), and superimposes it on the bias current of each electromagnet, thereby changing the attraction of the electromagnet on the front transverse force-bearing member 4 and the rear transverse force-bearing member 14, forming a closed-loop control, so that the output rod 16 always stays in the axial position; the axial stiffness of the spring 12 maintains the motion stability, realizes micron-level pointing positioning and meets the vibration isolation requirements of the load.

[0015] Compared with the prior art, the present invention has the following advantages: 1) This invention uses an electromagnet for active magnetic levitation radial constraint. With real-time feedback from an eddy current sensor, the radial stiffness can be dynamically adjusted, effectively suppressing the output rod yaw and achieving a pointing accuracy down to the micrometer level.

[0016] 2) The radial constraint force is provided by electromagnetic force, without mechanical contact, avoiding friction and wear, and is suitable for extreme environments such as vacuum and clean environments.

[0017] 3) Axial drive and radial constraint are decoupled, and large stroke (±25mm) linear motion is achieved through Lorentz force. At the same time, the spring provides axial passive vibration isolation, which combines large stroke and vibration isolation capabilities.

[0018] 4) The radial constraint force is provided by electromagnetic force, without mechanical contact, avoiding friction and wear, and is suitable for extreme environments such as vacuum and clean environments.

[0019] 5) The present invention avoids physical contact, complex mechanical transmission and maintenance problems in its structure, and solves the problem of complex control of existing actuators. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of the active magnetic levitation long-stroke vibration isolation pointing actuator of the present invention.

[0021] Figure 2 This is a schematic diagram of the internal structure of the active magnetic levitation long-stroke vibration isolation pointing actuator of the present invention.

[0022] Figure 3 This is a schematic diagram of the output rod of the active magnetic levitation long-stroke vibration isolation pointing actuator of the present invention.

[0023] Figure 4 This is a schematic diagram of the active magnetic levitation control principle of the present invention.

[0024] Figure 5 This is a schematic diagram of the active magnetic levitation structure of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 , Figure 2 As shown, the active magnetic levitation large-stroke vibration isolation pointing actuator of the present invention includes a housing 1, a sleeve 2, a sleeve connector 3, a front transverse force-bearing component 4, an eddy current sensor connector 5, an eddy current sensor 6, an air gap protection component 7, an electromagnet 8, a central rod 9, a coil 10, a magnet 11, a spring 12, a spring retaining ring 13, a rear transverse force-bearing component 14, and a base 15. like Figure 3 As shown, the output rod 16 includes a sleeve 2, a sleeve connector 3, a front transverse force-bearing component 4, a center rod 9, a coil 10, a spring retaining ring 13, and a rear transverse force-bearing component 14.

[0027] The coil 10 is fixed to the flange of the central rod 9, and the magnet 11 is fixed to the central support plate of the outer shell 1. The coil 10 and the magnet 11 are coaxial, forming a Lorentz force axial drive unit. The eddy current sensor connector 5, the air gap protection component 7, and the electromagnet 8 are fixed at the corresponding screw holes of the outer shell 1. The eddy current sensor 6 is fixed to the eddy current sensor connector 5 and is used to detect the radial displacement and yaw of the output rod 16 in real time. The front transverse force-bearing component 4 and the rear transverse force-bearing component 14 are respectively fixedly connected to both ends of the central rod 9 and are both made of magnetically conductive material. There are eight electromagnets 8 in total, divided into two groups, four in each group, which are centrally symmetrically installed on the outer shell 1 and are respectively opposite to the front transverse force-bearing component 4 and the rear transverse force-bearing component 14, forming a radial active magnetic suspension. Floating constraint; the spring 12 is sleeved on the outside of the central rod 9, one end of which is fixed to the central support plate of the outer shell 1 by the spring retaining ring 13, and the other end is fixed to the rear transverse force-bearing member 14 by the spring retaining ring 13, which is used to provide axial stiffness and maintain the axial zero position of the output rod 16; when the output rod 16 is radially offset by axial drive or external disturbance, the eddy current sensor 6 transmits the detection signal to the host computer, the host computer calculates the compensation current required by each electromagnet 8 according to the active control algorithm, and adjusts the attraction force of the electromagnet on the front transverse force-bearing member 4 and the rear transverse force-bearing member 14, so that the output rod 16 always stays in the axial position, realizing non-contact radial constraint; the spring 12 provides axial restoring force, so that the output rod 16 returns to the zero position when there is no axial drive.

[0028] By adjusting the current in the electromagnet 8, the equivalent radial stiffness between the actuator output rod 16 and the housing 1 can be dynamically adjusted; by replacing the spring 12 with a different stiffness, the axial stiffness can be adjusted.

[0029] In this embodiment, the front transverse force-bearing component 4 and the rear transverse force-bearing component 14 are made of electrical pure iron or high magnetic permeability material to enhance electromagnetic attraction.

[0030] In this embodiment, the spring 12 is a helical spring. Its two ends are clamped by the central support plate of the outer shell 1 and the spring fixing ring 13, and the rear transverse force-bearing member 14 and the spring fixing ring 13, respectively, so that the spring 12 is always in a compressed or stretched state, providing stable axial stiffness and a certain torsional stiffness. When the coil 10 is not energized, the actuator relies on the spring 12 to achieve passive vibration isolation.

[0031] In this embodiment, a minimum air gap of 0.5 mm is formed between the front transverse force-bearing component 4 and the corresponding four electromagnets 8; a minimum air gap of 0.5 mm is also formed between the rear transverse force-bearing component 14 and the corresponding four electromagnets 8; and a uniform gap of 0.4 mm is maintained between the air gap protection component 7 and the front transverse force-bearing component 4 and the rear transverse force-bearing component 14 to prevent accidental collisions.

[0032] When no current is applied to coil 10, the preload of spring 12 keeps output rod 16 in an axial equilibrium position.

[0033] like Figure 4 , Figure 5 The diagram shows the application of equal bias currents to eight electromagnets 8. This causes the front transverse force-bearing component 4 and the rear transverse force-bearing component 14 to be subjected to symmetrical initial attractive forces, and the output rod 16 is suspended near the central axis. The displacement or attitude data of the load installed on the sleeve 2 is acquired by external sensors, and the driving current of the coil 10 is generated according to the pointing control requirements. The interaction between the magnet 11 and the coil 10 generates an axial Lorentz force, which drives the output rod 16 to move axially and achieve a large stroke displacement. The radial yaw and deflection angle of the output rod 16 are monitored in real time by the eddy current sensor 6, and the signal is fed back to the host computer. The host computer calculates the adjustment current of the electromagnet 8 required to suppress the yaw according to the preset active control algorithm (such as PID control algorithm, sliding mode control algorithm, etc.). The currents are superimposed on the bias currents of each electromagnet, changing the attraction between the electromagnets and the front transverse force-bearing member 4 and the rear transverse force-bearing member 14, forming a closed-loop control, so that the output rod 16 always remains in the axial position; the axial stiffness of the spring 12 maintains motion stability, achieving micron-level pointing positioning and meeting the vibration isolation requirements of the load.

[0034] The working principle of this invention is as follows: When in the initial position, such as Figure 5 As shown, the axial and torsional stiffness provided by spring 12 keeps the output rod 16 in an axially balanced position and prevents axial rotation. Bias currents are applied to the four electromagnets symmetrically positioned at the front transverse force-bearing member 4 and the four electromagnets symmetrically positioned at the rear transverse force-bearing member 14, creating attractive forces on these members. Changing the bias current in each electromagnet balances the electromagnetic force on the output rod 16 with other forces. However, to keep the output rod 16 at its axial position, the eddy current sensor 6 monitors the degree of deviation of the output rod 16 and feeds it back to the host computer. The computer then calculates and changes the current in the electromagnet 8 so that the combined force and torque of the electromagnetic forces can pull the output rod back to its axial position. The air gap protection component 7 protects the electromagnets and eddy current sensor from impact by the output rod and provides initial support for the output rod 16.

[0035] When the actuator is working, current is input into coil 10. Since magnet 11 is placed coaxially with coil 10, coil 10 will be subjected to Lorentz force, causing output rod 16 to displace axially. However, since output rod 16 is subjected to the force of the load connected to the sleeve, and the base is constrained by the connected base plate, output rod 16 will deviate from the axis. Eddy current sensor 6 is needed to monitor the degree of deviation of output rod 16 and feed it back to the host computer. By calculating and changing the current of electromagnet 8, the combined force and torque of the electromagnetic force can pull the output shaft back to the axis.

[0036] The displacement data of the load mounted on sleeve 2 is acquired from an external sensor, and the input current of coil 8 is adjusted according to the control method and pointing requirements. Combined with high-precision external current control, the output force of output rod 16 is precisely controlled. This can meet the requirements of load vibration isolation, long-stroke pointing, and micron-level positioning accuracy.

Claims

1. An active magnetic levitation long-stroke vibration isolation pointing actuator, characterized in that: It includes a housing (1), a sleeve (2), a sleeve connector (3), a front transverse force-bearing component (4), an eddy current sensor connector (5), an eddy current sensor (6), an air gap protection component (7), an electromagnet (8), a center rod (9), a coil (10), a magnet (11), a spring (12), a spring retaining ring (13), a rear transverse force-bearing component (14), and a base (15). The output rod (16) consists of the sleeve (2), sleeve connector (3), front transverse force-bearing component (4), center rod (9), coil (10), spring retaining ring (13), and rear transverse force-bearing component (14). The coil (10) is fixed on the flange of the central rod (9), and the magnet (11) is fixed to the central support plate of the outer shell (1). The coil (10) and the magnet (11) are coaxial, forming a Lorentz force axial drive unit. The eddy current sensor connector (5), the air gap protection component (7), and the electromagnet (8) are fixed at the corresponding screw holes of the outer shell (1). The eddy current sensor (6) is fixed on the eddy current sensor connector (5) and is used to detect the radial displacement and yaw of the output rod (16) in real time. The front transverse force-bearing component (4) and the rear transverse force-bearing component (14) are fixedly connected to the two ends of the central rod (9). There are multiple electromagnets (8), which are divided into two groups. Multiple electromagnets in each group are centrally symmetrically installed on the outer shell (1) and are opposite to the front transverse force-bearing component (4) and the rear transverse force-bearing component (14) respectively, forming a radial force-bearing component. Active magnetic levitation constraint; the spring (12) is sleeved on the outside of the central rod (9), one end of which is fixed to the central support plate of the outer shell (1) by the spring fixing ring (13), and the other end is fixed to the rear transverse force-bearing member (14) by the spring fixing ring (13), which is used to provide axial stiffness and maintain the axial zero position of the output rod (16); when the output rod (16) is driven axially or causes radial displacement due to external disturbance, the eddy current sensor (6) transmits the detection signal to the host computer, the host computer calculates the compensation current required by each electromagnet (8), and adjusts the attraction force of the electromagnet on the front transverse force-bearing member (4) and the rear transverse force-bearing member (14) so ​​that the output rod (16) always stays in the axial position and realizes non-contact radial constraint; the spring (12) provides axial restoring force so that the output rod (16) returns to the zero position when there is no axial drive.

2. The active magnetic levitation long-stroke vibration isolation and pointing actuator according to claim 1, characterized in that: By adjusting the magnitude of the current in the electromagnet (8), the equivalent radial stiffness between the actuator output rod (16) and the housing (1) can be dynamically adjusted; by replacing the spring (12) with a different stiffness, the axial stiffness can be adjusted.

3. The active magnetic levitation long-stroke vibration isolation pointing actuator according to claim 1, characterized in that: The front transverse force-bearing component (4) and the rear transverse force-bearing component (14) are made of electrical pure iron or high magnetic permeability material to enhance electromagnetic attraction.

4. The active magnetic levitation long-stroke vibration isolation and pointing actuator according to claim 1, characterized in that: The spring (12) is a helical spring. Its two ends are clamped by the central support plate of the outer shell (1) and the spring fixing ring (13), and the rear transverse force-bearing member (14) and the spring fixing ring (13), respectively, so that the spring (12) is always in a compressed or stretched state, providing stable axial stiffness and a certain torsional stiffness; when the coil (10) is not energized, the actuator relies on the spring (12) to achieve passive vibration isolation.

5. The active magnetic levitation long-stroke vibration isolation and pointing actuator according to claim 1, characterized in that: An air gap is formed between the front transverse force-bearing component (4) and the corresponding electromagnet (8); an air gap is also formed between the rear transverse force-bearing component (14) and the corresponding electromagnet (8); the air gap protection component (7) maintains a uniform gap with the front transverse force-bearing component (4) and the rear transverse force-bearing component (14) to prevent accidental collisions.

6. The active magnetic levitation long-stroke vibration isolation and pointing actuator according to claim 5, characterized in that: A minimum air gap of 0.5 mm is formed between the front transverse force-bearing component (4) and the corresponding electromagnet (8); a minimum air gap of 0.5 mm is also formed between the rear transverse force-bearing component (14) and the corresponding electromagnet (8); and a uniform gap of 0.4 mm is maintained between the air gap protection component (7) and the front transverse force-bearing component (4) and the rear transverse force-bearing component (14).

7. The active magnetic levitation long-stroke vibration isolation and pointing actuator according to claim 1, characterized in that: There are eight electromagnets (8) in total, divided into two groups, with four in each group installed symmetrically on the outer shell (1).

8. The active magnetic levitation long-stroke vibration isolation and pointing actuator according to claim 1, characterized in that: When no current is applied to the coil (10), the preload of the spring (12) keeps the output rod (16) in an axial equilibrium position.

9. The active control method for the active magnetic levitation long-stroke vibration isolation pointing actuator according to any one of claims 1 to 8, characterized in that: Apply equal bias currents to multiple electromagnets (8) to cause the front transverse force-bearing member (4) and the rear transverse force-bearing member (14) to be subjected to symmetrical initial attractive forces, and the output rod (16) is suspended near the central axis; the displacement or attitude data of the load installed on the sleeve (2) is obtained through external sensors, and the driving current of the coil (10) is generated according to the pointing control requirements. The interaction between the magnet (11) and the coil (10) generates an axial Lorentz force, which drives the output rod (16) to move axially, realizing a large stroke displacement; the eddy current sensor (6) is used to realize the actual... The radial sway and deflection angle of the output rod (16) are monitored in real time, and the signal is fed back to the host computer. The host computer calculates the adjustment current of the electromagnet (8) required to suppress the sway according to the preset active control algorithm, and adds it to the bias current of each electromagnet. This changes the attraction of the electromagnet to the front transverse force-bearing component (4) and the rear transverse force-bearing component (14), forming a closed-loop control so that the output rod (16) always stays in the axial position. The axial stiffness of the spring (12) maintains the motion stability, realizes micron-level pointing positioning and meets the vibration isolation requirements of the load.

10. The active control method according to claim 9, characterized in that: The active control algorithm employs either PID control or sliding mode control.

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