Space reflector active vibration isolation platform based on piezoelectric amplification mechanism and working method of space reflector active vibration isolation platform

Abstract

The invention discloses a space reflector active vibration isolation platform based on a piezoelectric amplification mechanism and a working method of the space reflector active vibration isolation platform. The active vibration isolation platform comprises a reflector mounting platform, a base, a control module and three piezoelectric vibration isolation branched chains; each piezoelectric vibration isolation branch chain comprises a piezoelectric amplification mechanism unit and a sensing monitoring unit; each piezoelectric amplification mechanism unit comprises a piezoelectric amplification mechanism, a flexible hinge, a piezoelectric actuator and a pre-tightening assembly; the sensing unit comprises a first acceleration sensor and a second acceleration sensor. Active vibration isolation can be provided for micro-vibration in the three-degree-of-freedom direction of the space reflector under the complex working condition, the space reflector has the advantages of being high in displacement magnification factor, rapid in response, high in control precision and the like, and through the integrated design, the imaging precision of the space reflector is effectively guaranteed; the method has important application value and market potential in the fields of spaceflight optical remote sensing and the like.

Description

Technical Field

[0001] This invention relates to the fields of piezoelectric drive and mechanical vibration control, and in particular to an active vibration isolation platform for a space reflector based on a piezoelectric amplification mechanism and its working method. Background Technology

[0002] In aerospace optical remote sensing, space exploration, and high-precision observation, the imaging accuracy of space mirrors directly determines the success or failure of missions, and micro-vibration interference is a core factor restricting its accuracy improvement. Among these, piezoelectric drive technology, with its high displacement resolution, fast dynamic response, stable output force, and absence of electromagnetic interference, has become an ideal solution for active vibration isolation of space mirrors. However, traditional space mirror vibration isolation devices have significant drawbacks. They often employ a split-structure design, resulting in large size and low integration, making them unsuitable for the limited space environment and increasing system assembly errors. Performance-wise, they suffer from short piezoelectric drive displacement strokes and narrow micro-vibration suppression bandwidths, failing to cover the multi-frequency vibration interference under complex space conditions. Especially when facing the stringent requirements for attitude stability of space mirrors, traditional devices are prone to force coupling phenomena in multi-degree-of-freedom micro-vibration control, leading to mirror attitude deviations and severely affecting imaging quality, thus limiting their application in high-resolution optical payloads. Developing a highly integrated, large-stroke magnification, and low-coupling-interference active vibration isolation platform for space mirrors has become an important direction for overcoming the accuracy bottleneck of aerospace optical equipment. Moreover, in the extreme environment of space, the material properties and structural stability of traditional vibration isolation devices are easily affected, further exacerbating the difficulty of micro-vibration control and leading to insufficient environmental adaptability and long-term reliability of the vibration isolation system. This is the main challenge currently facing the development of space mirror vibration isolation technology. This invention breaks through the limitations of existing space mirror vibration isolation technology, significantly improving the accuracy of micro-vibration suppression and environmental adaptability. Its application scope can meet the high-precision vibration isolation requirements of multiple scenarios such as high-resolution remote sensing satellites, space telescopes, and deep space exploration optical payloads, and it has important engineering application value. Summary of the Invention

[0003] This invention aims to overcome the shortcomings mentioned in the background art and proposes a vibration suppression structure for a space mirror based on piezoelectric composite materials and its implementation method.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] An active vibration isolation platform for a space reflector based on a piezoelectric amplification mechanism, the overall structure of which consists of a reflector mounting platform, a base platform, a control module and three piezoelectric vibration isolation branches;

[0006] The three piezoelectric vibration isolation branches have the same structure, each including a piezoelectric amplification mechanism unit and a sensing and monitoring unit;

[0007] The piezoelectric amplification mechanism units have the same structure, each including an upper double-layer elliptical flexible hinge, a lower straight circular flexible hinge, a piezoelectric actuator, an amplification bracket, a pre-tightened lower T-shaped boss, and a lower flexible hinge connector;

[0008] The reflector mounting platform is an equilateral triangular plate structure with an overall triangular outline. The plate has three oblong through holes and seven circular mounting holes symmetrically arranged radially with the center point as the symmetrical point. There are also three reinforcing ribs and a hollowed-out pentagonal area inside.

[0009] The base platform has a three-branch symmetrical layout. The center is a connecting area with a circular arc transition, and three rectangular branches extend outward at a 120° angle. Each rectangular branch has multiple threaded holes, and the central circular arc section has an array of threaded holes and a through hole. The bottom surface of the base platform is set as a flat mounting surface for connecting with the vibration source that needs to be fixed to the vibration isolation object. The base design takes into account both symmetry and installation adaptability, and can provide a stable support foundation for the upper mechanism.

[0010] The pre-tightening lower T-shaped boss consists of a lower rectangular base and an upper boss with a 45° inclined surface. The lower rectangular base is a cuboid structure with symmetrical oblong straight slots on the top for installation and fixation with the base. The upper boss is wedge-shaped with one side being an inclined surface at a 45° angle, connecting to one edge of the lower base. The boss has a circular through hole and a coaxial oblong straight slot for connection and pre-tightening with the bottom end of the piezoelectric actuator. The lower flexible hinge connector is a rectangular plate structure with three points distributed along the central axis. The connector features symmetrical elongated oval straight slots, with the central slot longer than the two side slots. A larger but identically shaped elongated oval profile is nested outside the central slot, forming a double-layered elongated oval structure. The two side slots are of the same size and symmetrically distributed at both ends of the connector. The lower circular flexible hinge is a modular block structure composed of upper and lower parts. The upper part is rectangular with a rounded top edge and two threaded holes for installation and fixing. The lower part connects to the upper part with an arc-shaped groove design. The overall profile matches the upper structure, forming... The symmetrical circular flexible connection area also has a threaded hole at the bottom for installation and fixing; the piezoelectric actuator is a cylindrical structure, the main body of which consists of alternating layers of ground electrode plates, circular ceramic plates, and circular electrode plates. All ceramic plates are polarized along the thickness direction and adjacent ceramic plates have opposite polarization directions. The top is a stud with external threads, and the bottom end face has a threaded hole and a positioning groove; the magnification bracket is a long strip-shaped inclined plate structure, with a gradually changing shape that is narrow at one end and wide at the other. The narrow section has an inclined pointed design, and the top is equipped with a... The mounting surface has rounded corners and threaded holes for connecting with the upper double-layer elliptical flexible hinge. The wide section has a rectangular through hole with rounded corners and a rectangular notch below, with circular mounting holes distributed inside. The upper double-layer elliptical flexible hinge is a combined columnar structure, consisting of two cylindrical sections and a flexible connection area. One end is a rectangular block structure with studs extending from the side, and the other end is a cylindrical section with threaded holes. The middle flexible area contains two elliptical flexible connection sections distributed vertically, each composed of symmetrical arc surfaces.

[0011] The first three accelerometers are respectively installed on the upper end of the upper double-layer elliptical flexible hinge cylinder, on the surface of the reflector mounting platform, and on the side away from the piezoelectric vibration isolation branch. They are used to collect vibration feedback signals of the reflector mounting platform in the Z-axis direction under the overall coordinate system. The second three accelerometers are respectively installed on the rear end of the pre-tightened lower T-shaped boss, on the surface of the base platform, and on the side close to the piezoelectric vibration isolation branch. They are used to collect vibration feedforward signals of the vibration source in the X-axis, Y-axis, and Z-axis directions under the overall coordinate system.

[0012] The three piezoelectric vibration isolation branches are arranged in a triangular array on the surface of the base platform. The reflector mounting platform is located at the geometric center of the three piezoelectric vibration isolation branches and is rigidly connected to the upper double-layer flexible hinge of each branch through a straight groove on its lower surface. The cylindrical section of the double-layer flexible hinge is coplanar with the lower surface of the reflector mounting platform and coaxial with the straight groove on the lower surface. The pre-tightened lower T-shaped boss of each vibration isolation branch is fixed to the base through straight grooves on both sides. The circular through hole on its inclined surface forms a coaxial assembly relationship with the corresponding hole of the piezoelectric actuator base. In the modular layout, the three piezoelectric vibration isolation branches The smooth mounting surface at the top of the narrow section of the amplification mechanism remains coplanar. The stud extending from the upper double-layer flexible hinge is coaxially assembled with the pre-set threaded hole on the smooth mounting surface and maintains vertical assembly accuracy. The end face of the rectangular block of the upper double-layer flexible hinge near the stud is coplanar with the smooth mounting surface. The piezoelectric vibration isolation branch achieves spatial vibration control through a three-branch symmetrical configuration. The amplification mechanisms in two adjacent vibration isolation brackets are set with an axial difference of 120°. Each vibration isolation branch is connected to the corresponding installation area. The axes of all amplification mechanisms are collinear with the center symmetry line of the rectangular branch plane of their base.

[0013] The control module is a controller, which is connected to the first and second accelerometers of the three piezoelectric vibration isolation branches, and to the three channels driving the vibration of the piezoelectric vibration isolation branches. The controller processes the feedback vibration signal collected by the first accelerometer and the feedforward vibration data collected by the second accelerometer in real time, and dynamically adjusts the filter coefficients of each channel. Specifically, the controller automatically optimizes the control parameters of each driving channel by continuously comparing the minimum mean square error between the actual vibration response and the desired target value, using the gradient descent method, thereby achieving precise phase compensation and amplitude adjustment of the output force of the driving components.

[0014] 2. The space reflector active vibration isolation platform based on the piezoelectric amplification mechanism according to claim 1 is characterized in that the reflector mounting platform is provided with a plurality of bolt holes, which can be used to connect with the space reflector base or other vibration isolation objects.

[0015] 3. The working method of the space reflector active vibration isolation platform based on the piezoelectric amplification mechanism as described in claim 1, characterized in that it includes the following steps:

[0016] For each vibration isolation module in the first to third piezoelectric vibration isolation branches:

[0017] Step 1), Vibration signal acquisition and input; A first accelerometer is set on the reflector mounting platform to acquire the platform vibration feedback signal in real time; A second accelerometer is set on the base platform to acquire the vibration source feedforward signal synchronously; The two signals are converted by the signal conditioner and then transmitted synchronously to the controller, where the reference signal is used as the system input signal and the error signal is used as the feedback basis for closed-loop control, thus constructing a "feedforward + feedback" dual signal input system;

[0018] Step 2), Feedforward and Feedback Signal Processing: The controller performs composite processing on the reference signal and the error signal. First, it eliminates noise and clutter by passing a bandpass filter. Then, it inputs the reference signal into the frequency response functions of the three identified control channels to generate three Filtered-x signals. At the same time, the reference signal is calculated by three adaptive filters to obtain the initial controller output signal, which provides a benchmark for subsequent optimization.

[0019] Step 3) Drive signal iterative optimization; construct a closed-loop iterative mechanism based on the Filtered-x algorithm: input the error signal and the Filtered-x signal into the controller, take the residual vibration energy as the optimization target, calculate the convolution value of the reference signal and the real-time residual signal through the LMS algorithm, and dynamically adjust the adaptive filter weight coefficients using the gradient descent method to continuously optimize the output signal; at the same time, combine the feedforward signal to predict the vibration transmission path, and correct the phase shift through the feedback signal to ensure that the output signal has amplitude conservation and phase reversal characteristics.

[0020] Step 4), control signal output and vibration suppression; the optimized three output signals are amplified by a power amplifier and then applied to the piezoelectric actuators of the three piezoelectric vibration isolation branches respectively; the actuators pass through d 33 The pattern generates longitudinal vibration, which is amplified by the amplification mechanism and then converted into vibrations in the Z-axis and circumferential direction by the upper double-layer flexible hinge mechanism. Axis flip, rotation The reverse vibration in the axis reversal direction cancels out the original vibration with equal amplitude and opposite phase. The residual vibration signal after real-time acquisition and control is used as a new error signal and sent back to the controller to form a complete closed loop of "acquisition-processing-optimization-execution-feedback", which continuously attenuates the vibration energy and achieves high-precision vibration isolation control. Taking the longitudinal vibration of the Z-axis of the overall coordinate system controlled by the vibration isolation module as an example, the control module applies the same-phase A-phase signal (the amplitude of the A-phase signal is equal to that of the B-phase signal and the phase difference is 180°) to the control channel of the three piezoelectric vibration isolation branches, triggering the piezoelectric actuators of each branch to produce axial same-amplitude and same-phase expansion and contraction deformation. This deformation is transmitted and amplified by the amplification mechanism to the reflector mounting platform, so that the three branches produce vibrations that are opposite in phase, same frequency and same amplitude as the vibration source, achieving equal amplitude and opposite phase cancellation with the original vibration waveform.

[0021] Through the above steps, the three piezoelectric vibration isolation branches are driven to generate vibrations in the Z-direction and circumferential direction relative to the vibration source, respectively. Axis flip, rotation The system employs a force that is precisely reversed in the direction of axis flipping. Relying on real-time vibration feedback data from the first and second accelerometers, and combined with the Fx-LMS algorithm, the system dynamically adjusts the phase and amplitude of the output signals of each channel. This actively cancels out and continuously attenuates the vibration energy in the target area of ​​the reflector mounting platform, ultimately achieving a significant reduction in the vibration amplitude of the system in key degrees of freedom, thus ensuring the imaging accuracy of the space reflector.

[0022] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0023] 1. This invention employs independent control via three signals, and through a piezoelectric amplification mechanism, it can precisely achieve Z-axis longitudinal and circumferential control. Axis flip, rotation The axis-flipping three-degree-of-freedom vibration control covers the key attitude dimensions of space mirror imaging, eliminating the need for redundant degree-of-freedom design, further optimizing the system's lightweight design and control efficiency, and meeting core vibration isolation requirements.

[0024] 2. The piezoelectric amplification mechanism has a fast response and high precision, with independent control of 3 channels without coupling. The displacement amplification factor of the piezoelectric amplification mechanism can reach 3-4 times, which greatly improves the accuracy of micro-vibration compensation, effectively suppresses micro-vibration, and ensures the stability of the mirror imaging posture. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the piezoelectric vibration isolation branch in this invention;

[0027] Figure 3 This is a schematic diagram of the upper double-layer flexible hinge structure of the piezoelectric vibration isolation branch in this invention;

[0028] Figure 4 This is a schematic diagram of the lower straight circular flexible hinge structure of the piezoelectric vibration isolation branch in this invention;

[0029] Figure 5 This is a schematic diagram of the base platform structure in this invention;

[0030] Figure 6 This is a schematic diagram of the structure of the mirror mounting platform in this invention;

[0031] Figure 7 This is a schematic diagram of the operation of the enlarged piezoelectric vibration isolation branch mechanism in this invention;

[0032] Figure 8 This is a schematic diagram comparing the deformation of the active vibration isolation working mode of the present invention for longitudinal vibration in the Z-axis direction;

[0033] Figure 9 This invention is aimed at the XOY plane and A schematic diagram comparing the deformation of the active vibration isolation working modes of axial bending vibration;

[0034] Figure 10 This invention is aimed at the XOY plane and A schematic diagram comparing the deformation of the active vibration isolation working modes of axial bending vibration;

[0035] Figure 11 This invention is aimed at the XOY plane and A schematic diagram comparing the deformation of the active vibration isolation working mode under bending vibration at a 30° included angle in the positive direction of the axis;

[0036] Figure 12 This invention is aimed at the XOY plane and A schematic diagram comparing the deformation of the active vibration isolation working mode under bending vibration at a 60° included angle in the negative axial direction;

[0037] Figure 13 This is a block diagram of the parallel centralized three-channel control of the LMS algorithm of this invention;

[0038] Figure 14 This is a channel relationship diagram of the parallel centralized three-channel control of the present invention;

[0039] Figure 15 This is a schematic diagram of the vibration control principle of the present invention;

[0040] In the diagram, 1-reflector mounting platform, 2-piezoelectric vibration isolation branch, 3-base platform. Detailed Implementation

[0041] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0042] This invention can be implemented in many different forms and should not be considered limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully express the scope of the invention to those skilled in the art. In the drawings, components are enlarged for clarity. The global coordinate system XYZ of the base platform and the local coordinate system of the reflector mounting platform are defined in the figures.

[0043] like Figure 1 As shown, this invention discloses an active vibration isolation platform for a space reflector based on a piezoelectric amplification mechanism. Its overall structure consists of a reflector mounting platform, a base platform, a control module, and three piezoelectric vibration isolation branches. For ease of description, the three piezoelectric vibration isolation branches are numbered sequentially in the figure.

[0044] The first to third piezoelectric vibration isolation branches have the same structure, each including a piezoelectric amplification mechanism unit and a sensing and monitoring unit. The three piezoelectric vibration isolation branches are distributed in a triangular array on the surface of the base platform. The reflector mounting platform is located at the geometric center of the three piezoelectric vibration isolation branches and is rigidly connected to the upper double-layer flexible hinge of each branch through a straight groove on the lower surface. The cylindrical section of the double-layer flexible hinge is coplanar with the lower surface of the reflector mounting platform and coaxial with the straight groove on the lower surface. The pre-tightened lower T-shaped boss of each vibration isolation branch is fixed to the base through straight grooves on both sides, and its inclined circular through hole forms a coaxial connection with the corresponding hole of the piezoelectric actuator bottom base. In the modular layout, the smooth mounting surfaces at the top of the narrow section of the amplification mechanism in the three piezoelectric vibration isolation branches remain coplanar. The studs extending from the upper double-layer flexible hinge are coaxially assembled with the pre-set threaded holes on the smooth mounting surface and maintain vertical assembly accuracy. The end face of the upper double-layer flexible hinge rectangular block near the stud is coplanar with the smooth mounting surface. The piezoelectric vibration isolation branches achieve spatial vibration control through a three-branch symmetrical configuration. The amplification mechanisms in two adjacent vibration isolation brackets are set with an axial difference of 120°. Each vibration isolation branch is connected to the corresponding installation area. The axes of all amplification mechanisms are collinear with the center symmetry line of the rectangular branch plane of their base.

[0045] The control module is a controller, which is connected to the first and second accelerometers of the three piezoelectric vibration isolation branches, and to the three channels driving the vibration of the piezoelectric vibration isolation branches. The controller processes the feedback vibration signal collected by the first accelerometer and the feedforward vibration data collected by the second accelerometer in real time, and dynamically adjusts the filter coefficients of each channel. Specifically, the controller automatically optimizes the control parameters of each driving channel by continuously comparing the minimum mean square error between the actual vibration response and the desired target value, using the gradient descent method, thereby achieving precise phase compensation and amplitude adjustment of the output force of the driving components.

[0046] like Figure 2 As shown, the piezoelectric amplification mechanism units have the same structure, each including an upper double-layer elliptical flexible hinge, a lower straight circular flexible hinge, a piezoelectric actuator, an amplification bracket, a pre-tightened lower T-shaped boss, and a lower flexible hinge connector.

[0047] The magnifying bracket is a long, sloping plate structure with a gradually changing shape, narrow at one end and wide at the other. The narrow section has an inclined, pointed design with a smooth mounting surface with rounded corners at the top. The mounting surface has threaded holes for connection with the upper double-layer elliptical flexible hinge. The wide section has a rectangular through-hole with rounded corners and a rectangular notch at the bottom, with circular mounting holes distributed inside for fixed installation with the lower circular flexible hinge. The piezoelectric actuator has a cylindrical structure, the main body of which consists of alternating layers of grounding electrode plates, circular ceramic plates, and circular electrode plates. All ceramic plates are polarized along their thickness direction, and adjacent ceramic plates have opposite polarization directions. The top is a stud with external threads, and the bottom end face has a threaded hole and a positioning groove. The pre-tightening lower T-shaped boss consists of a lower rectangular base and an upper boss with a 45° slope. The lower rectangular base is a cuboid structure with symmetrical oblong straight slots on the top for installation and fixation with the base platform. The upper boss is wedge-shaped with one side being an inclined surface at a 45° angle, connecting to one side edge of the lower base. The boss has a circular through hole and a coaxial oblong straight slot for connection and pre-tightening with the bottom end of the piezoelectric actuator. The lower flexible hinge connector is a rectangular plate structure with three oblong straight slots symmetrically distributed along the central axis. The middle oblong straight slot is longer than the two side slots, and a larger but similarly shaped oblong outline is nested outside the middle slot, forming a double-layer oblong structure for fixed installation with the lower circular flexible hinge. The two side slots are the same size and symmetrically distributed at both ends of the connector for fixed installation with the base platform.

[0048] like Figure 3 As shown, the upper double-layer elliptical flexible hinge is a combined columnar structure, consisting of two cylindrical sections and a flexible connection area. One end is a rectangular block structure with studs extending from the side, and the other end is a cylindrical section with threaded holes. The middle flexible area contains two elliptical flexible connection sections distributed vertically, each consisting of a symmetrical arc surface.

[0049] like Figure 4 As shown, the lower circular flexible hinge is a combined block structure, consisting of two parts, the upper part is rectangular, the top edge is rounded, and it has two threaded holes for installation and fixing. The lower part and the upper part are connected by an arc groove design. The overall outline matches the upper structure to form a symmetrical circular flexible connection area. The bottom of the lower part also has threaded holes for installation and fixing.

[0050] like Figure 5As shown, the base has a three-branch symmetrical layout. The center is a connecting area with a circular arc transition, and three rectangular branches extend outward at a 120° angle. Each rectangular branch has multiple threaded holes, and the central arc segment has an array of threaded holes and a through hole. The bottom surface of the base platform is set as a flat mounting surface for connecting with the vibration source that needs to be fixed to the vibration isolation object. The base design takes into account both symmetry and installation adaptability, and can provide a stable support foundation for the upper mechanism.

[0051] The second acceleration sensors are respectively installed at the rear end of the pre-tightened T-shaped boss, on the surface of the base platform, and on the side near the piezoelectric vibration isolation branch. There are a total of three sensors, which are used to collect vibration feedforward signals of the vibration source in the X-axis direction, Y-axis direction, and Z-axis direction in the overall coordinate system.

[0052] like Figure 6 As shown, the reflector mounting platform is an equilateral triangular plate structure with an overall triangular outline. The plate has three radially symmetrical elongated through holes and seven circular mounting holes distributed around the center point, which are connected to the space reflector or other vibration isolation objects. The interior also has three reinforcing ribs and a hollowed-out pentagonal area.

[0053] The first acceleration sensors are respectively set on the upper end of the upper double-layer elliptical flexible hinge cylinder, on the surface of the reflector mounting platform, and on the side near the direction of the piezoelectric vibration isolation branch. There are a total of three sensors, which are used to collect vibration feedback signals in the Z-axis direction of the reflector mounting platform in the overall coordinate system.

[0054] like Figure 7 As shown, when the piezoelectric actuator in the piezoelectric vibration isolation branch receives an electrical signal excitation, it will pass through d 33 The vibration mode generates a first-order longitudinal vibration; under this mode, the piezoelectric ceramic sheet undergoes expansion and contraction along the actuator axis, achieving displacement output at point A; the output displacement at point A is amplified by the lever mechanism of the amplification bracket, and a larger displacement is output at point B, which is then transmitted to the reflector mounting platform.

[0055] like Figure 8 As shown, for longitudinal vibration in the Z-axis direction, the principle of active vibration isolation in this invention is to apply in-phase signals to the control channels of all piezoelectric vibration isolation branches. The amplitudes of the A-phase signal and the B-phase signal are equal, and their phases differ by 180°. Taking the application of the A-phase driving voltage to the control channels of all piezoelectric vibration isolation branches as an example, the piezoelectric actuators of the three piezoelectric vibration isolation branches simultaneously generate axial expansion and contraction deformations with the same amplitude and phase. This deformation is transmitted and amplified to the reflector mounting platform via an amplification mechanism. Ultimately, the vibration generated by the three piezoelectric vibration isolation branches is opposite in phase, consistent in frequency, and has the same amplitude as the vibration of the vibration source. That is, the vibration and the vibration of the vibration source can cancel each other out, achieving the effect of vibration control.

[0056] like Figure 9 As shown, for the XOY plane For axial bending vibration, the principle of active vibration isolation in this invention is to apply phase A signals to the control channels of the second and third piezoelectric vibration isolation branches, and phase B signals to the control channel of the first piezoelectric vibration isolation branch. This ensures that the vibration amplitudes of the second and third piezoelectric vibration isolation branches are equal to those of the first piezoelectric vibration isolation branch, but opposite in phase. Specifically, when the vibration displacements of the second and third piezoelectric vibration isolation branches reach their maximum extension, the first piezoelectric vibration isolation branch is at its minimum shortening. The vibrations from the three piezoelectric vibration isolation branches are amplified by an amplification mechanism and transmitted to the reflector mounting platform. The resulting vibration is opposite in phase, consistent in frequency, and identical in amplitude to the vibration from the vibration source. This means that the vibration from the second and third branches cancels out the vibration from the vibration source, achieving vibration control. Figure 10 As shown, for the XOY plane and For axial bending vibration, the principle of active vibration isolation in this invention is to apply an A-phase signal to the second piezoelectric vibration isolation branch and a B-phase signal to the control channel of the third piezoelectric vibration isolation branch. This makes the vibration amplitudes of the second and third piezoelectric vibration isolation branches equal but opposite in phase. The vibrations of the second and third piezoelectric vibration isolation branches are amplified by the amplification mechanism to the reflector mounting platform. The resulting vibration is opposite in phase, consistent in frequency, and equal in amplitude to the vibration of the vibration source. In other words, the vibration of the second and third piezoelectric vibration isolation branches can cancel each other out, achieving the effect of vibration control.

[0057] like Figure 11 As shown, for the XOY plane For bending vibrations at a 30° angle in the positive direction of the axis, the active vibration isolation principle of this invention is to apply a phase A signal to the control channels of the first and second piezoelectric vibration isolation branches, and a phase B signal to the control channel of the third piezoelectric vibration isolation branch. This ensures that the vibration amplitudes of the first, second, and third piezoelectric vibration isolation branches are equal but opposite in phase. The vibrations from the three piezoelectric vibration isolation branches are amplified by a multi-amplifier mechanism and transmitted to the reflector mounting platform. The resulting vibration is opposite in phase, consistent in frequency, and identical in amplitude to the vibration from the vibration source. In other words, the vibration from the first, second, and third piezoelectric vibration isolation branches cancels out the vibration from the vibration source, achieving vibration control. Figure 12 As shown, for the XOY plane For bending vibrations at a 60° angle in the negative direction of the axis, the principle of active vibration isolation in this invention is to apply phase A signals to the control channels of the first and third piezoelectric vibration isolation branches and phase B signals to the control channel of the second piezoelectric vibration isolation branch. This ensures that the vibration amplitudes of the first and third piezoelectric vibration isolation branches are equal to those of the second piezoelectric vibration isolation branch, but opposite in phase. The vibrations of the three piezoelectric vibration isolation branches are amplified by an amplification mechanism and transmitted to the reflector mounting platform. The resulting vibration is opposite in phase, consistent in frequency, and identical in amplitude to the vibration of the vibration source. In other words, the vibration of this vibration and the vibration of the vibration source can cancel each other out, achieving the effect of vibration control.

[0058] like Figure 13 As shown, in the control system of this invention, the reference signal X(n) is obtained in real time through a second sensor and serves as the input signal for the entire system; the reference signal is controlled by three identified control channel frequency response functions (respectively...). The Fx-LMS algorithm generates three filtered-x signals (v1(n), v2(n), and v3(n)). These three filtered-x signals play a crucial role in the iterative calculations of the Fx-LMS algorithm, serving as the basis for dynamically adjusting the weight function and continuously optimizing the control effect. Simultaneously, the reference signal X(n) passes through three adaptive filters (W1(z), W2(z), and W3(z)) to obtain controller output signals (u1(n), u2(n), and u3(n)). These three output signals then pass through three control channels H1(z), H2(z), and H3(z), including three piezoelectric actuators, to obtain three control system outputs y1(n), y2(n), and y3(n), respectively. The three control systems interact with the disturbance response δ. d,1 (n), δ d，2 (n), δ d，3 The three error signals e1(n), e2(n), and e3(n) are superimposed to form three error signals; the three error signals are measured by the first sensor and participate in the dynamic adjustment process of the weight function together with the three filtered-x signals.

[0059] like Figure 14As shown, the signal transmission relationship of this invention is as follows: The first sensor converts the signal through a signal conditioner to obtain a feedback signal (i.e., an error signal), which is then transmitted to the corresponding controllers. Each controller independently calculates based on its corresponding feedback signal to generate corresponding control commands. The output signals of the three controllers are amplified by a power amplifier, and the drive signals are applied to the three piezoelectric actuators. After vibration amplification by the amplification mechanism, precise control of the reflector mounting platform is achieved. The control system adopts a parallel centralized design. The feedback signals of the three control channels are independently calculated and transmitted to their respective piezoelectric actuators, thereby achieving efficient micro-vibration control. This structure ensures that each channel works independently, effectively reducing mutual interference between systems. The feedforward signal serves as the system's reference signal and is provided by the second sensor. The acceleration signal measured by this sensor serves as the system's input, helping the controller to perform more accurate calculations and control. By combining with the feedback signal, the feedforward signal can improve the system's response speed and control accuracy, ensuring effective suppression of micro-vibrations.

[0060] like Figure 15 As shown, the acceleration signals measured by the first and second sensors are converted by a signal conditioner and then transmitted to the controller. Inside the controller, these signals are processed and displayed on the host computer, while the controller's output signal is calculated. The output signal is further amplified by a power amplifier, and finally, the drive signal is applied to three piezoelectric actuators to achieve control of the micro-vibration of the structure. The host computer is developed using LabVIEW software and undertakes multiple functions such as data acquisition, control calculation, and communication to ensure the stable operation and efficient control of the system. Through the hardware architecture and control strategy of this invention, technical support and theoretical basis are provided for the active control of micro-vibration of a space reflector.

[0061] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0062] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An active vibration isolation platform for a space reflector based on a piezoelectric amplification mechanism, the overall structure of which consists of a reflector mounting platform, a base platform, a control module, and three piezoelectric vibration isolation branches; The three piezoelectric vibration isolation branches have the same structure, each including a piezoelectric amplification mechanism unit and a sensing and monitoring unit; The piezoelectric amplification mechanism units have the same structure, each including an upper double-layer elliptical flexible hinge, a lower straight circular flexible hinge, a piezoelectric actuator, an amplification bracket, a pre-tightened lower T-shaped boss, and a lower flexible hinge connector; The reflector mounting platform is an equilateral triangular plate structure with an overall triangular outline. The plate has three oblong through holes and seven circular mounting holes symmetrically arranged radially with the center point as the symmetrical point. There are also three reinforcing ribs and a hollowed-out pentagonal area inside. The base platform has a three-branch symmetrical layout. The center is a connecting area with a circular arc transition, and three rectangular branches extend outward at a 120° angle. Each rectangular branch has multiple threaded holes, and the central circular arc section has an array of threaded holes and a through hole. The bottom surface of the base platform is set as a flat mounting surface for connecting with the vibration source that needs to be fixed to the vibration isolation object. The base design takes into account both symmetry and installation adaptability, and can provide a stable support foundation for the upper mechanism. The pre-tightening lower T-shaped boss consists of a lower rectangular base and an upper boss with a 45° inclined surface. The lower rectangular base is a cuboid structure with symmetrical oblong straight slots on the top for installation and fixation with the base. The upper boss is wedge-shaped with one side having a 45° inclined surface that connects to one edge of the lower base. The boss has a circular through hole and a coaxial oblong straight slot for connection and pre-tightening with the bottom end of the piezoelectric actuator. The lower flexible hinge connector is a rectangular plate structure with three oblong straight slots symmetrically distributed along the central axis. The length of the central elongated straight groove is greater than that of the two side straight grooves, and a larger but identically shaped elongated outline is nested outside the central straight groove, forming a double-layered elongated structure. The two side straight grooves are of the same size and are symmetrically distributed at both ends of the connector. The lower elongated flexible hinge is a combined block structure, consisting of upper and lower parts. The upper part is rectangular with a rounded transition at the top edge and has two threaded holes for installation and fixing. The lower part has an arc-shaped groove design at the connection between the upper and lower parts, and the overall outline matches the upper structure, forming a symmetrical circular flexible connection area. The bottom of the lower part also has threaded holes for installation and fixing. The piezoelectric actuator is a cylindrical structure. The main body is composed of alternately stacked grounding electrode plates, circular ceramic plates, and circular electrode plates. All ceramic plates are polarized along the thickness direction, and the polarization direction of adjacent ceramic plates is... Conversely, the top is a stud with external threads, and the bottom end face has a threaded hole and a positioning groove; the magnifying bracket is a long strip-shaped inclined plate structure, with a gradually changing shape that is narrow at one end and wide at the other. The narrow section has an inclined pointed design, and the top has a smooth mounting surface with rounded corners. The mounting surface has a threaded hole for connecting with the upper double-layer elliptical flexible hinge, and the wide section has a rectangular through hole with rounded corners, a rectangular notch at the bottom, and circular mounting holes distributed inside; the upper double-layer elliptical flexible hinge is a combined columnar structure, consisting of two cylindrical sections and a flexible connecting area. One end is a rectangular block structure with a stud extending from the side, and the other end is a cylindrical section with a threaded hole. The middle flexible area contains two elliptical flexible connecting sections distributed vertically, each consisting of a symmetrical arc surface; The first three accelerometers are respectively installed on the upper end of the upper double-layer elliptical flexible hinge cylinder, on the surface of the reflector mounting platform, and on the side away from the piezoelectric vibration isolation branch. They are used to collect vibration feedback signals of the reflector mounting platform in the Z-axis direction under the overall coordinate system. The second three accelerometers are respectively installed on the rear end of the pre-tightened lower T-shaped boss, on the surface of the base platform, and on the side close to the piezoelectric vibration isolation branch. They are used to collect vibration feedforward signals of the vibration source in the X-axis, Y-axis, and Z-axis directions under the overall coordinate system. The three piezoelectric vibration isolation branches are arranged in a triangular array on the surface of the base platform. The reflector mounting platform is located at the geometric center of the three piezoelectric vibration isolation branches and is rigidly connected to the upper double-layer flexible hinge of each branch through a straight groove on its lower surface. The cylindrical section of the double-layer flexible hinge is coplanar with the lower surface of the reflector mounting platform and coaxial with the straight groove on the lower surface. The pre-tightened lower T-shaped boss of each vibration isolation branch is fixed to the base through straight grooves on both sides. The circular through hole on its inclined surface forms a coaxial assembly relationship with the corresponding hole of the piezoelectric actuator base. In the modular layout, the three piezoelectric vibration isolation branches The smooth mounting surface at the top of the narrow section of the amplification mechanism remains coplanar. The stud extending from the upper double-layer flexible hinge is coaxially assembled with the pre-set threaded hole on the smooth mounting surface and maintains vertical assembly accuracy. The end face of the rectangular block of the upper double-layer flexible hinge near the stud is coplanar with the smooth mounting surface. The piezoelectric vibration isolation branch achieves spatial vibration control through a three-branch symmetrical configuration. The amplification mechanisms in two adjacent vibration isolation brackets are set with an axial difference of 120°. Each vibration isolation branch is connected to the corresponding installation area. The axes of all amplification mechanisms are collinear with the center symmetry line of the rectangular branch plane of their base. The control module is a controller, which is connected to the first and second accelerometers of the three piezoelectric vibration isolation branches, and to the three channels driving the vibration of the piezoelectric vibration isolation branches. The controller processes the feedback vibration signal collected by the first accelerometer and the feedforward vibration data collected by the second accelerometer in real time, and dynamically adjusts the filter coefficients of each channel. Specifically, the controller automatically optimizes the control parameters of each driving channel by continuously comparing the minimum mean square error between the actual vibration response and the desired target value, using the gradient descent method, thereby achieving precise phase compensation and amplitude adjustment of the output force of the driving components.

2. The space reflector active vibration isolation platform based on the piezoelectric amplification mechanism according to claim 1 is characterized in that the reflector mounting platform is provided with a plurality of bolt holes, which can be used to connect with the space reflector base or other vibration isolation objects.

3. The working method of the space reflector active vibration isolation platform based on the piezoelectric amplification mechanism as described in claim 1, characterized in that it includes the following steps: For each vibration isolation module in the first to third piezoelectric vibration isolation branches: Step 1). Vibration signal acquisition and input: A first accelerometer is set on the reflector mounting platform to acquire the platform vibration feedback signal in real time; a second accelerometer is set on the base platform to acquire the vibration source feedforward signal synchronously; the two signals are converted by the signal conditioner and then transmitted synchronously to the controller, where the reference signal is used as the system input signal and the error signal is used as the feedback basis for closed-loop control, thus constructing a "feedforward + feedback" dual signal input system; Step 2), Feedforward and Feedback Signal Processing: The controller performs composite processing on the reference signal and the error signal. First, it eliminates noise and clutter by passing a bandpass filter. Then, it inputs the reference signal into the frequency response functions of the three identified control channels to generate three Filtered-x signals. At the same time, the reference signal is calculated by three adaptive filters to obtain the initial controller output signal, which provides a benchmark for subsequent optimization. Step 3) Drive signal iterative optimization; construct a closed-loop iterative mechanism based on the Filtered-x algorithm: input the error signal and the Filtered-x signal into the controller, take the residual vibration energy as the optimization target, calculate the convolution value of the reference signal and the real-time residual signal through the LMS algorithm, and dynamically adjust the adaptive filter weight coefficients using the gradient descent method to continuously optimize the output signal; at the same time, combine the feedforward signal to predict the vibration transmission path, and correct the phase shift through the feedback signal to ensure that the output signal has amplitude conservation and phase reversal characteristics. Step 4), Control Signal Output and Vibration Suppression: The optimized three output signals are amplified by a power amplifier and then applied to the piezoelectric actuators of the three piezoelectric vibration isolation branches respectively; the actuators pass through d 33 The pattern generates longitudinal vibration, which is amplified by the amplification mechanism and then converted into vibrations in the Z-axis and circumferential direction by the upper double-layer flexible hinge mechanism. Axis flip, rotation The reverse vibration in the axis reversal direction cancels out the original vibration with equal amplitude and opposite phase. The residual vibration signal after real-time acquisition and control is used as a new error signal and fed back to the controller, forming a complete closed loop of "acquisition-processing-optimization-execution-feedback", continuously attenuating the vibration energy and achieving high-precision vibration isolation control. Taking the longitudinal vibration of the Z-axis of the overall coordinate system controlled by the vibration isolation module as an example, the control module applies the same-phase A-phase signal (the amplitude of the A-phase signal is equal to that of the B-phase signal and the phase difference is 180°) to the control channel of the three piezoelectric vibration isolation branches, triggering the piezoelectric actuators of each branch to produce axial same-amplitude and same-phase expansion and contraction deformation. This deformation is transmitted and amplified by the amplification mechanism to the reflector mounting platform, so that the three branches produce vibrations that are opposite in phase, same frequency and same amplitude as the vibration source, achieving equal amplitude and opposite phase cancellation with the original vibration waveform. Through the above steps, the three piezoelectric vibration isolation branches are driven to generate vibrations in the Z-direction and circumferential direction relative to the vibration source, respectively. Axis flip, rotation The system employs a force that is precisely reversed in the direction of axis flipping. Relying on real-time vibration feedback data from the first and second accelerometers, and combined with the Fx-LMS algorithm, the system dynamically adjusts the phase and amplitude of the output signals of each channel. This actively cancels out and continuously attenuates the vibration energy in the target area of ​​the reflector mounting platform, ultimately achieving a significant reduction in the vibration amplitude of the system in key degrees of freedom, thus ensuring the imaging accuracy of the space reflector.

Images