A three-stage micro-vibration isolation system and method combining active and passive

Abstract

This invention belongs to the technical field of micro-vibration control and discloses a three-level micro-vibration isolation system and method combining active and passive vibration control. The system includes a controlled structure, an active control unit, and a passive control unit. The active and passive control units work together to form three-level micro-vibration control for the controlled unit. The passive control unit includes a first passive control module and a second passive control module. The first passive control module includes a shell, a negative stiffness damper, and a suspension cable. The suspension cable connects the controlled structure and the shell. The suspension cable, damper, and controlled structure together form a long-period pendulum structure to filter out mid-to-high frequency micro-vibrations relative to its oscillation period. The second passive control module provides vertical passive vibration isolation to filter out three-dimensional low-frequency micro-vibrations. The active control unit compensates for vibrations caused by ground-level micro-vibrations. This invention solves the problem of low-frequency and high-frequency micro-vibrations in space optical equipment.

Description

Technical Field

[0001] This invention belongs to the technical field of micro-vibration control, and more specifically, relates to a three-level micro-vibration isolation system and method that combines active and passive vibration control. Background Technology

[0002] Large-scale space optical equipment (such as space telescopes and space cameras) is an important tool for cutting-edge scientific exploration and safeguarding national defense security. Before launch and deployment, large-scale space optical equipment needs to undergo a series of tests on the ground, especially optical imaging performance tests simulating on-orbit operating environments (vacuum, cryogenics) to verify its on-orbit performance. However, during the testing process, space optical equipment is highly sensitive to external vibrations; even small magnitudes of external vibration can lead to inaccurate experimental results. Therefore, vibration isolation control systems are often required in environmental simulation test facilities.

[0003] In recent years, with the increasing scale and complexity of space optical equipment, the requirements for vibration isolation performance of the ring mode test device's vibration isolation system have also increased. For optical remote sensing satellites, the micro-vibration problems they face are characterized by small magnitudes and wide bandwidth; however, current vibration isolation system solutions are insufficient to meet the requirements for low-frequency, micro-vibration control. Therefore, it is urgent to research and explore new solutions for vibration isolation systems in the low-frequency, micro-vibration field for next-generation large-scale space optical equipment ring mode test devices. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a three-level micro-vibration isolation system and method that combines active and passive methods to solve the problem of low-frequency and high-frequency micro-vibration of space optical equipment.

[0005] To achieve the above objectives, according to one aspect of the present invention, a three-stage micro-vibration isolation system combining active and passive vibration control is provided. This system includes a controlled structure, an active control unit, and a passive control unit. The active and passive control units work together to provide three-stage micro-vibration control for the controlled structure, wherein:

[0006] The passive control unit includes a first passive control module and a second passive control module. The first passive control module includes a housing, a negative stiffness damper, and a sling. The controlled structure is located in the center of the housing. Multiple negative stiffness dampers are evenly distributed in the circumferential direction of the housing and are connected to the inner wall of the housing through the negative stiffness dampers. The sling is used to connect the controlled structure and the housing. The sling, the controlled structure, and the negative stiffness damper form a long-period pendulum structure to filter out mid-to-high frequency micro-vibrations relative to its pendulum period. The second passive control module includes a vibration isolator located above the housing. The vibration isolator is connected to the housing and is used to provide vertical passive vibration isolation to filter out three-dimensional low-frequency micro-vibrations.

[0007] The active control unit is located above the second passive control module and is connected to the housing through the second passive control module. It is used to compensate for vibrations caused by micro-vibrations of the ground.

[0008] More preferably, the active control unit includes a guide rail, an actuator, and a control center. The guide rail is grounded at both ends. The actuator is mounted on the guide rail, and its lower end is connected to the housing through the second passive control module. The control center is connected to the actuator. After the ground generates micro-vibrations, the control center controls the actuator to move on the guide rail according to the micro-vibrations of the ground, thereby compensating for the micro-vibrations generated by the ground.

[0009] More preferably, the active control unit further includes a sensor connected to the control center for detecting micro-vibrations generated on the ground and transmitting the micro-vibrations to the control center.

[0010] More preferably, the active control unit employs an optimal control algorithm from modern control theory.

[0011] More preferably, the vibration isolators are multiple in number and are evenly and symmetrically distributed along the circumference.

[0012] More preferably, the vibration isolator is made of rubber.

[0013] More preferably, the oscillation period of the controlled structure is:

[0014]

[0015] Where T0 is the period of the simple pendulum:

[0016]

[0017] m is the mass of the controlled structure, l is the equivalent length of the sling, -k is the negative stiffness, and g is the high-precision gravitational acceleration at the experimental location.

[0018] More preferably, the period amplification factor of the controlled structure is:

[0019]

[0020] Where η is the periodic amplification factor.

[0021] More preferably, the number of negative stiffness dampers is multiple, symmetrically distributed along the circumference, used to increase the vibration period of the pendulum structure and reduce its natural frequency.

[0022] According to another aspect of the present invention, a method for constructing the optimal parameters of the above-described three-level micro-vibration isolation system is provided, the method comprising the following steps:

[0023] S1 sets an ultra-low frequency, ultra-wide bandwidth vibration load on the guide rail to simulate ground pulsation in the environment;

[0024] S2 constructs the finite element optimization model of the three-level micro-vibration isolation system, with the equivalent length of the suspension cable and the negative stiffness values ​​of the negative stiffness dampers in each direction as optimization targets, and the preset maximum angular velocity of the pendulum structure as constraint conditions.

[0025] S3 solves the finite element optimization model to obtain the equivalent length of the sling and the negative stiffness values ​​of the dampers in each direction.

[0026] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0027] 1. The active-passive three-level micro-vibration control system provided by the present invention utilizes the active control unit, the second passive control module for lateral shear isolation, and the suspension-negative stiffness pendulum structure formed by the first passive control module to control low-frequency and high-frequency micro-vibrations from the horizontal and vertical directions respectively, thereby achieving effective control of the three-level micro-vibrations of the controlled structure.

[0028] 2. The micro-vibration control system provided by this invention is a system for controlling the micro-vibration of precision structures. When local pulsation or external structural vibration causes the control structure to vibrate, the active control unit controls the actuator to move horizontally based on feedback data from high-precision sensors through an active optimal control algorithm, thereby controlling the horizontal vibration of the entire system.

[0029] 3. The multi-stage vibration reduction mechanism provided by this invention has an active control as the first stage, which does not directly control the sway of the controlled structure, while the first passive control module of the suspension cable-negative stiffness directly controls the main controlled structure, thereby ensuring the reliability and stability of the entire system. Attached Figure Description

[0030] Figure 1 This is a three-dimensional structural schematic diagram of a micro-vibration control system constructed according to a preferred embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the structural principle of the micro-vibration control system constructed according to a preferred embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of a negative stiffness pendulum constructed according to a preferred embodiment of the present invention.

[0033] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0034] 1-Guide rail, 2-Actuator, 3-Vibration isolator, 4-Housing, 5-Sling, 6-Controlled structure, 7-Negative stiffness damper, 8-Sensor, 9-Control center. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0036] A three-stage micro-vibration isolation system combining active and passive vibrations includes a guide rail 1, an actuator 2, a vertical vibration isolator 3, a sling 5, a housing 4, a controlled structure 6, a damper with negative stiffness 7, a sensor 8, and a control center 9.

[0037] The active control unit, comprising guide rail 1, actuator 2, sensor 8, and control center 9, is the first-level control unit. The vibration isolator is the second passive control module, representing the second level of control. The sling 5, shell 4, controlled structure 6, and negative stiffness damper 7 form the third-level passive control module, thus creating a multi-level vibration isolation mechanism to achieve multi-directional vibration reduction and better control of the structure's micro-vibrations. This three-level micro-vibration isolation system can achieve three levels of control—a hybrid of active and passive in the horizontal direction—as well as passive control in the vertical direction. The active control, being the first-level control method, does not directly participate in controlling the controlled structure 6, while the passive control method directly controls the controlled structure 6, thereby ensuring the reliability of the entire control system.

[0038] The guide rail 1 is connected to the base at both ends, and the micro-vibration load of the base is transmitted to the controlled structure through the guide rail 1; the actuator 2 is installed on the lower edge of the guide rail 1 and can move horizontally on the guide rail 1, and can receive control signals from the control center 9; all structures below the actuator 2 are suspended, ensuring that the source of external load can only be transmitted to the main structure through the guide rail 1.

[0039] In this embodiment, there are four vertical passive vibration isolators 3, symmetrically distributed, used to connect the actuator 2 and the structural shell 4. They are the main load-bearing structures of the entire system, providing the main vertical passive vibration isolation and some lateral passive vibration isolation. They are made of high-performance rubber vibration isolation material. Due to the characteristics of rubber, it can provide vertical stiffness support and passive vibration reduction performance at the same time. At the same time, the shear energy dissipation performance of rubber can also provide some lateral vibration reduction effect. This is the second level of horizontal passive control.

[0040] The controlled structure 6 is connected to the structural shell 4 above by four symmetrically distributed suspenders of equivalent length l, and to the side wall of the structural shell 4 by four symmetrically distributed negative stiffness dampers 7. This swing passive control system provides the third level of horizontal passive control.

[0041] Sensors 8 are evenly installed on guide rail 1 to transmit micro-vibration data of the base to control center 9 in real time. Control center 9 uses a high-precision filtering algorithm to synthesize an estimated excitation with minimal error from multiple sensor data and the actual excitation. It then uses an optimal control algorithm to provide real-time displacement data to actuator 2 based on the estimated excitation, driving actuator 2 to move along guide rail 1 according to the command, thereby realizing the first level of horizontal active control.

[0042] The pendulum structure composed of slings and negative stiffness dampers can significantly increase the natural period of the controlled structure 6, thereby effectively controlling the ultra-low frequency and ultra-wideband load conditions faced by the satellite.

[0043] In the system consisting of slings and dampers, the period of the controlled structure 6 is:

[0044]

[0045] Where T0 is the period of the simple pendulum:

[0046]

[0047] m is the mass of the controlled structure, l is the equivalent length of the sling, -k is the negative stiffness, and g is the high-precision gravitational acceleration at the experimental location.

[0048] The amplification factor of the controlled structure for 6 periods is:

[0049]

[0050] The method for determining the optimal parameters in the above-mentioned active-passive three-stage micro-vibration control system includes the following steps:

[0051] S1 uses the power spectrum method to generate a series of ultra-low frequency, ultra-wideband vibration loads; and uses Simulink to perform finite element modeling of the system.

[0052] S2 uses numerical simulation to determine the maximum structural angular velocity that affects experimental accuracy; the active control algorithm is the optimal control algorithm.

[0053] S3 uses numerical algorithms to simulate the maximum angular velocity and root mean square angular velocity values ​​corresponding to different cable lengths and negative stiffness. Using data from the uncontrolled state as a reference, it draws a three-dimensional control performance diagram and finds the optimal parameters for the equivalent cable length and the magnitude of negative stiffness in each direction that conform to actual engineering.

[0054] Preferably, the active control unit uses the optimal control algorithm in modern control theory, which can most closely approximate the ideal optimal control situation.

[0055] Preferably, there are four dampers 7 with negative stiffness, which are symmetrically distributed and connect the controlled structure 6 to the outer wall of the structure. This can significantly increase the vibration period of the original pendulum structure and reduce its natural frequency.

[0056] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A three-stage micro-vibration isolation system combining active and passive vibration isolation, characterized in that, The system includes a controlled structure (6), an active control unit, and a passive control unit. The active control unit and the passive control unit work together to form a three-level micro-vibration control for the controlled structure, wherein: The passive control unit includes a first passive control module and a second passive control module. The first passive control module includes a housing (4), a negative stiffness damper (7), and a sling (5). The controlled structure (6) is located in the center of the housing (4). Multiple negative stiffness dampers (7) are evenly distributed in the circumferential direction of the housing (4). The negative stiffness dampers (7) are connected to the inner wall of the housing (4) through the negative stiffness dampers (7). The sling (5) is used to connect the controlled structure (6) and the housing (4). The sling (5), the negative stiffness damper (7), and the controlled structure (6) form a long-period pendulum structure to filter out the mid-to-high frequency micro-vibrations relative to its oscillation period. The second passive control module includes a vibration isolator (3) located above the housing (4). The vibration isolator (3) is connected to the housing (4) to provide vertical passive vibration isolation to filter out three-dimensional low-frequency micro-vibrations. The active control unit is located above the second passive control module and is connected to the housing (4) through the second passive control module. It is used to compensate for vibrations caused by micro-vibrations of the ground.

2. The three-stage micro-vibration isolation system combining active and passive vibration as described in claim 1, characterized in that, The active control unit includes a guide rail (1), an actuator (2) and a control center (9). The guide rail (1) is grounded at both ends. The actuator (2) is mounted on the guide rail (1) and its lower end is connected to the housing (4) through the second passive control module. The control center (9) is connected to the actuator (2). After the ground generates micro-vibration, the control center (9) controls the actuator (2) to move on the guide rail (1) according to the micro-vibration of the ground, thereby compensating for the micro-vibration generated by the ground.

3. The three-stage micro-vibration isolation system combining active and passive vibration as described in claim 2, characterized in that, The active control unit also includes a sensor (8) connected to the control center (9) for detecting micro-vibrations generated on the ground and transmitting the micro-vibrations to the control center (9).

4. A three-stage micro-vibration isolation system combining active and passive vibration as described in claim 2 or 3, characterized in that, The active control unit employs the optimal control algorithm based on modern control theory.

5. A three-stage micro-vibration isolation system combining active and passive vibration as described in claim 2, characterized in that, The vibration isolators (3) are multiple in number and are evenly and symmetrically distributed along the circumference.

6. The three-stage micro-vibration isolation system combining active and passive vibration as described in claim 2, characterized in that, The vibration isolator (3) is made of rubber.

7. The three-stage micro-vibration isolation system combining active and passive vibration as described in claim 2, characterized in that, The oscillation period of the controlled structure is: in, The period of a simple pendulum: It is the quality of the controlled structure. This is the equivalent length of the sling. Negative stiffness To test local high-precision gravitational acceleration.

8. The three-stage micro-vibration isolation system combining active and passive vibration as described in claim 7, characterized in that, The period amplification factor of the controlled structure is: in, It is the period amplification factor.

9. A three-stage micro-vibration isolation system combining active and passive vibration as described in claim 2, characterized in that, The negative stiffness dampers (7) are numerous and symmetrically distributed along the circumference to increase the vibration period of the pendulum structure and reduce its natural frequency.

10. A method for constructing the optimal parameters of a three-stage micro-vibration isolation system according to any one of claims 2-9, characterized in that, The method includes the following steps: S1 sets an ultra-low frequency, ultra-wide bandwidth vibration load on the guide rail to simulate ground pulsation in the environment; S2 Construct the finite element optimization model of the three-level micro-vibration isolation system, with the equivalent length of the suspension cable and the negative stiffness values ​​of the negative stiffness dampers in each direction as optimization targets, and the preset maximum angular velocity of the pendulum structure as constraint conditions. S3 Solve the finite element optimization model to obtain the optimal equivalent length of the sling and the negative stiffness values ​​of the negative stiffness dampers in each direction.

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