Longitudinal bending composite type six-degree-of-freedom piezoelectric active vibration isolation platform and working method thereof

Abstract

The invention discloses a longitudinal bending composite type six-degree-of-freedom piezoelectric active vibration isolation platform and a working method thereof. The vibration isolation platform adopts a modular structural design, a vibration isolation connecting platform and a base platform are sequentially arranged from top to bottom and are connected through four uniformly distributed vibration isolation modules, and each vibration isolation module forms a multi-stage vibration transmission structure through a fixed base, a transducer base, a piezoelectric transducer, an amplitude-change pole, a pre-tightening bolt and a small flexible hinge. The control module collects feedback signals of a first acceleration sensor arranged on the vibration isolation connecting platform and feedforward signals of a second acceleration sensor arranged on the base platform, and outputs 12-channel control signals to the piezoelectric transducers of the vibration isolation modules after signal processing. The piezoelectric transducer is driven to generate a composite motion mode of longitudinal vibration and multidirectional bending vibration, and active suppression of longitudinal vibration and radial bending vibration in any direction of a vibration isolation object is achieved. The device has the advantages of multi-degree-of-freedom vibration isolation, compact structure, lightweight design, independent control, high stability and the like, and has important application value in the fields of space reflecting mirrors, micro-nano manufacturing equipment vibration control and multi-degree-of-freedom vibration isolation systems.

Description

Technical Field

[0001] This invention relates to the fields of piezoelectric drive and mechanical vibration control, and in particular to a longitudinal bending composite six-degree-of-freedom piezoelectric active vibration isolation platform and its working method. Background Technology

[0002] Active vibration isolation platforms play a crucial role in numerous fields such as aerospace, engineering machinery, and mechanical transmission, effectively reducing the vibration amplitude of isolated objects. Piezoelectric materials, with their advantages of fast response, strong resistance to electromagnetic interference, high precision, and lightweight design, are particularly well-suited for use in active vibration isolation platforms. However, traditional active vibration isolation platforms suffer from several drawbacks: they are heavy and structurally complex, posing challenges to manufacturing and maintenance, hindering their use in certain specialized scenarios, and exhibiting slow response and excessive hysteresis. Especially in multi-degree-of-freedom vibration scenarios, traditional active vibration isolation platforms struggle to meet isolation requirements, limiting their application scope and resulting in poor isolation performance. Therefore, developing a compact, lightweight, independently controllable, and highly stable active vibration isolation platform has become a critical research direction. Furthermore, in modern complex engineering and technological environments, the vibration coupling effect in multi-degree-of-freedom vibration control presents challenges for decoupling active vibration isolation platforms. Traditional methods struggle to achieve precise decoupling control, leading to decreased system control accuracy and stability. This is the main problem currently facing the development of this type of active vibration isolation platform. This invention breaks through the existing technical bottlenecks of active vibration isolation platforms, significantly improving the adaptive control accuracy and response speed of vibration isolation systems. Its application scope can meet the high-precision vibration isolation needs of multiple industries such as aerospace precision instrument protection, engineering machinery powertrain noise reduction, and mechanical transmission system vibration suppression, and has significant application value. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings mentioned in the background art and proposes a spacecraft vibration suppression structure 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] A longitudinal bending composite six-degree-of-freedom piezoelectric active vibration isolation platform, the overall structure of which consists of a vibration isolation connection platform, a base platform, a control module and first to fourth vibration isolation modules;

[0006] The first to fourth vibration isolation modules have the same structure, each including a fixed base, a transducer base, a piezoelectric transducer, an amplitude transformer, a preload bolt, and a small flexible hinge;

[0007] The fixed base has four threaded blind holes arranged in an array on its bottom surface and one of its side surfaces; the transducer base has a countersunk through hole at the center of its upper boss for the preload bolt to pass through; the base has five threaded blind holes of the same diameter and coaxiality with the side holes of the fixed base in its circumference and center; the piezoelectric transducer adopts a dual-unit composite structure, consisting of alternating layers of grounding electrode plates, square ceramic plates, and square electrode plates, wherein the front unit contains two sets of square piezoelectric ceramic plates with opposite polarization directions, and the rear unit is configured with two sets of spatially orthogonally distributed dual-zone ceramic plates. All ceramic plates are polarized along the thickness direction and adjacent ceramic plates have opposite polarization directions. Their outer contour matches the cross-section of the amplitude transformer base boss. The piezoelectric transducer has a through hole at its center for the preload bolt to pass through; the square electrode plate in the piezoelectric transducer has the same shape and cross-sectional area as the square ceramic plate. The square electrode plate is connected to the control module via a wire to receive control signals. This allows the vibration isolation module to generate the required longitudinal or bending vibration. The amplitude transformer adopts an irregular structure design, with the front end being a small square prism with a circular through hole to achieve bending constraint, and the rear end being a square prism with the same cross-sectional area as the front end through quarter-elliptical symmetrical cutting. Experiments have verified that when the elliptical surface shape coefficient is optimized to 0.08, the vibration transmission efficiency and stability of the amplitude transformer reach the best matching state. The two are integrally formed and threaded blind holes are set in the square prism. The pre-tightening bolt passes through the transducer base and the center hole of the piezoelectric transducer in sequence and is then threadedly connected to the amplitude transformer to form an axial prestress loading mechanism. The small flexible hinge consists of four parts: the first part is a cylinder with a small cross-sectional area, which is connected to the threaded countersunk hole on the side wall of the vibration isolation connection platform; the second part is a square prism; the third part is a necked cylinder; and the fourth part is a cylinder with a threaded through hole, which is connected to the small square prism with a circular through hole at the front end of the amplitude transformer.

[0008] The first four accelerometers are respectively installed on the side wall of a small square prism with a circular through hole at the front end of the amplitude rod, away from the direction of the vibration isolation connection platform. All of them are triaxial sensors and are used to collect vibration feedback signals of the vibration isolation connection platform in the X-axis, Y-axis and Z-axis directions in the overall coordinate system. The second accelerometer is installed at the center of the base platform and is a triaxial sensor. It is used to collect vibration feedforward signals of the vibration source in the X-axis, Y-axis and Z-axis directions in the overall coordinate system.

[0009] Both the vibration isolation connecting platform and the base platform are square flat plates. The vibration isolation connecting platform has four threaded through holes for connecting to the vibration isolation object. Each of the four sides of the vibration isolation connecting platform has a threaded countersunk hole near the corner of the platform, which is connected by a small flexible hinge. The base platform has four pairs of rounded corner grooves at symmetrical positions at one-third of the length of adjacent sides. The symmetrical distribution of these grooves can effectively avoid assembly misalignment or interference caused by processing errors. The bottom surface of the base platform is set as a flat mounting surface for connecting to the vibration source that needs to be fixed to the vibration isolation object. While ensuring structural stability, the tolerance characteristics of the grooves improve assembly adaptability.

[0010] The four vibration isolation modules are arranged in a rectangular array on the surface of the base platform. The vibration isolation connecting platform is located at the geometric center of the four vibration isolation modules and is rigidly connected to the small flexible hinges of each module through the side wall. The square prism transition section in the small flexible hinge is coplanar with the side wall of the vibration isolation connecting platform. The fixed base of each vibration isolation module is fixed to the base platform through the bottom threaded hole. The threaded hole on its side and the corresponding hole of the transducer base form a coaxial assembly relationship. In the modular layout, the cross-sections of the upper bosses of the transducer bases in the first and third vibration isolation modules are parallel to each other. The cross-sections of the upper bosses of the transducer bases in the second and fourth vibration isolation modules are parallel to each other. The sides of the fixed bases of adjacent vibration isolation modules are arranged orthogonally. The bottom surface of all fixed bases is perpendicular to the base platform. The amplitude rod assembly realizes spatial vibration control through axial orthogonal configuration. The amplitude rods in two adjacent vibration isolation modules are axially perpendicular to each other. The amplitude rods of the diagonally distributed modules are axially parallel. The axes of all amplitude rods are orthogonal to the plane of their transducer bases.

[0011] The control module is a controller, connected to the first and second accelerometers in the first to fourth vibration isolation modules, and further connected to the 12 channels that drive the vibration of the vibration isolation modules. The controller processes the feedback vibration signal from the first accelerometer and the feedforward vibration data from the second accelerometer in real time, dynamically adjusting the filter coefficients of each channel. Specifically, the controller automatically optimizes the control parameters of each drive channel by continuously comparing the minimum mean square error between the actual vibration response and the desired target value, using the gradient descent method to achieve precise phase compensation and amplitude adjustment of the output force of the drive components.

[0012] 2. The longitudinal bending composite six-degree-of-freedom piezoelectric active vibration isolation platform according to claim 1 is characterized in that the vibration isolation connection platform is provided with a number of bolt holes, which can be used to connect with the vibration isolation object.

[0013] 3. The working method of the longitudinal bending composite six-degree-of-freedom piezoelectric active vibration isolation platform according to claim 1, characterized in that it includes the following steps:

[0014] For each of the first to fourth vibration isolation modules:

[0015] Step 1) Collect vibration signals; install the first accelerometer on the vibration isolation connection platform to collect the platform vibration feedback signal in real time; install the second accelerometer on the base platform to collect the vibration source feedforward signal synchronously; the two sensors respectively acquire time-domain signals containing vibration frequency and amplitude, and transmit the dual signals synchronously to the control module to build the data input basis for closed-loop control;

[0016] Step 2) Processing feedforward and feedback signals; The control module performs composite processing on the dual signals: First, it eliminates environmental noise and high-frequency clutter through a bandpass filter, and then performs phase reversal operation; The feedforward signal is used to predict the vibration transmission path, and the phase offset is corrected in real time through the feedback signal to generate a control signal with amplitude conservation and phase reversal characteristics. The controller realizes the fusion calculation of feedforward compensation and feedback correction to form an adaptive signal processing closed loop.

[0017] Step 3) Iterative optimization of the driving signal: Establish a closed-loop iterative mechanism with residual vibration energy as the optimization target, continuously collect the residual vibration signal of the vibration isolation connection platform as a new feedback quantity, input it into the transverse filter to generate a reference signal; use the LMS algorithm to dynamically calculate the convolution value of the reference signal and the real-time residual signal, and adjust the filter weight coefficients step by step through the gradient descent method to complete the iterative optimization of the driving signal.

[0018] Step 4) Output vibration control signal; distribute the processed control signal to the 12-channel drive array, monitor the residual disturbance signal after vibration control in real time, and send it back to the controller as the feedback input for the next control cycle, forming a complete closed-loop control chain of "signal acquisition-processing-execution-feedback"; taking the longitudinal vibration in the Z-axis direction of the overall coordinate system controlled by the vibration isolation module as an example, the control module sends a specific phase excitation voltage to the B channel of the four vibration isolation modules, triggering the piezoelectric transducer to generate a local coordinate system. Shaft bending vibration; after being amplified by the amplitude transformer, the vibration is converted into the reverse vibration wave of the Z-axis of the vibration isolation connection platform through the small flexible hinge mechanism, so as to achieve equal amplitude and opposite phase cancellation with the original vibration waveform.

[0019] Through the above steps, the piezoelectric actuator is driven to generate a force that is precisely opposite in phase to the vibration source. Based on real-time vibration feedback data, the output phase and amplitude are dynamically adjusted so that the vibration energy in the target area is actively canceled and continuously attenuated, thereby reducing the vibration amplitude of the system.

[0020] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0021] 1. This invention employs 12-channel signal control, which can realize multi-degree-of-freedom vibration control of the vibration isolation platform. Whether it is longitudinal vibration, bending vibration, torsion or translation of the vibration isolation connection platform, a better vibration control effect can be achieved by applying different excitation methods to the 12 channels of the control module.

[0022] 2. The present invention has a compact layout and excellent performance. Even if a single vibration isolation module malfunctions, other vibration isolation modules can achieve a certain vibration control effect based on the iterative feedback signal. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention;

[0024] Figure 2 This is a schematic diagram of the vibration isolation module in this invention;

[0025] Figure 3 This is a schematic diagram of the small flexible hinge structure of the vibration isolation module in this invention;

[0026] Figure 4 This is a schematic diagram of the base platform in this invention;

[0027] Figure 5 This is a schematic diagram of the transducer of the vibration isolation module in this invention;

[0028] Figure 6 The amplitude transformer rod in the vibration isolation module of this invention is Schematic diagram of bending vibration deformation in the axial direction;

[0029] Figure 7 This is a comparative diagram of the deformation of the active vibration isolation working mode of the present invention for longitudinal vibration;

[0030] Figure 8 This is a comparative deformation diagram of the active vibration isolation working mode of the present invention for bending vibration in the 45° direction of the XY plane;

[0031] Figure 9 This is a schematic diagram comparing the deformation of the active vibration isolation working mode of the present invention for bending vibration in the 135° direction of the XY plane;

[0032] Figure 10 This is a comparative diagram of deformation of the active vibration isolation working mode for XY plane translation according to the present invention;

[0033] Figure 11 This is a block diagram of the LMS algorithm used in the controller of this invention;

[0034] Figure 12 This is a schematic diagram of the vibration control principle of the present invention;

[0035] In the diagram, 1-fourth vibration isolation module, 2-vibration isolation connection platform, 3-base platform. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0037] 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 vibration isolation platform and the local coordinate system of the vibration isolation module are defined in the figures.

[0038] like Figure 1 As shown, this invention discloses a longitudinal bending composite six-degree-of-freedom piezoelectric active vibration isolation platform, which includes a vibration isolation connection platform, a base platform, a control module, and first to fourth vibration isolation modules. For ease of description, the four vibration isolation modules are numbered sequentially in the figure.

[0039] The first to fourth vibration isolation modules have the same structure, each including a fixed base, a transducer base, a piezoelectric transducer, an amplitude transformer, a preload bolt, and a small flexible hinge;

[0040] The first acceleration sensors are respectively installed on the side wall of the small square prism with a circular through hole at the front end of the amplitude rod, on the side away from the vibration isolation connection platform. There are four sensors in total, which are used to collect vibration feedback signals of the vibration isolation connection platform in the X-axis, Y-axis and Z-axis directions in the overall coordinate system. The second acceleration sensor is installed at the center of the base platform, which is used to collect vibration feedforward signals of the vibration source in the X-axis, Y-axis and Z-axis directions in the overall coordinate system.

[0041] Both the vibration isolation connecting platform and the base platform are square flat plates. The vibration isolation connecting platform has four threaded through holes for connecting to the vibration isolation object. Each of the four sides of the vibration isolation connecting platform has a threaded countersunk hole near the corner of the platform, which is connected by a small flexible hinge. The base platform has four pairs of rounded corner grooves at symmetrical positions at one-third of the length of adjacent sides. The symmetrical distribution of these grooves can effectively avoid assembly misalignment or interference caused by processing errors. The bottom surface of the base platform is set as a flat mounting surface for connecting to the vibration source that needs to be fixed to the vibration isolation object. While ensuring structural stability, the tolerance characteristics of the grooves improve assembly adaptability.

[0042] The four vibration isolation modules are arranged in a rectangular array on the surface of the base platform. The vibration isolation connecting platform is located at the geometric center of the four vibration isolation modules and is rigidly connected to the small flexible hinges of each module through the side wall. The square prism transition section in the small flexible hinge is coplanar with the side wall of the vibration isolation connecting platform. The fixed base of each vibration isolation module is fixed to the base platform through the bottom threaded hole. The threaded hole on its side and the corresponding hole of the transducer base form a coaxial assembly relationship. In the modular layout, the cross-sections of the upper bosses of the transducer bases in the first and third vibration isolation modules are parallel to each other. The cross-sections of the upper bosses of the transducer bases in the second and fourth vibration isolation modules are parallel to each other. The sides of the fixed bases of adjacent vibration isolation modules are arranged orthogonally. The bottom surface of all fixed bases is perpendicular to the base platform. The amplitude rod assembly realizes spatial vibration control through axial orthogonal configuration. The amplitude rods in two adjacent vibration isolation modules are axially perpendicular to each other. The amplitude rods of the diagonally distributed modules are axially parallel. The axes of all amplitude rods are orthogonal to the plane of their transducer bases.

[0043] The control module is a controller, connected to the first and second accelerometers in the first to fourth vibration isolation modules, and further connected to the 12 channels that drive the vibration of the vibration isolation modules. The controller processes the feedback vibration signal from the first accelerometer and the feedforward vibration data from the second accelerometer in real time, dynamically adjusting the filter coefficients of each channel. Specifically, the controller automatically optimizes the control parameters of each drive channel by continuously comparing the minimum mean square error between the actual vibration response and the desired target value, using the gradient descent method to achieve precise phase compensation and amplitude adjustment of the output force of the drive components.

[0044] like Figure 2As shown, the fixed base has four threaded blind holes arranged in an array on its bottom surface and one of its side surfaces; the transducer base has a countersunk through hole at the center of its upper boss for the preload bolt to pass through; the base has five threaded blind holes of the same diameter and coaxial with the side holes of the fixed base in its circumference and center; the piezoelectric transducer adopts a dual-unit composite structure, consisting of alternating layers of grounding electrode plates, square ceramic plates, and square electrode plates, wherein the front unit contains two sets of square piezoelectric ceramic plates with opposite polarization directions, and the rear unit is configured with two sets of spatially orthogonally distributed dual-zone ceramic plates. All ceramic plates are polarized along the thickness direction and adjacent ceramic plates have opposite polarization directions. Its outline matches the cross-section of the boss of the amplitude transformer base. The piezoelectric transducer has a through hole at its center for the preload bolt to pass through; the square electrode plate in the piezoelectric transducer has the same shape and cross-sectional area as the square ceramic plate. The square electrode plate is connected to the control module via a wire to receive control signals. The signal enables the vibration isolation module to generate the required longitudinal or bending vibration. The amplitude transformer adopts an irregular structure design, with the front end being a small square prism with a circular through hole to achieve bending constraint, and the rear end being a square prism with the same cross-sectional area as the front end through quarter-elliptical symmetrical cutting. Experiments have verified that when the elliptical surface shape coefficient is optimized to 0.08, the vibration transmission efficiency and stability of the amplitude transformer reach the best matching state. The two are integrally formed and threaded blind holes are set in the square prism. The pre-tightening bolt passes through the transducer base and the piezoelectric transducer center hole in sequence and is then threadedly connected to the amplitude transformer to form an axial prestress loading mechanism. The small flexible hinge consists of four parts: the first part is a cylinder with a small cross-sectional area, which is connected to the threaded countersunk hole on the side wall of the vibration isolation connection platform; the second part is a square prism; the third part is a necked cylinder; and the fourth part is a cylinder with a threaded through hole, which is connected to the small square prism with a circular through hole at the front end of the amplitude transformer.

[0045] like Figure 3 As shown, the small flexible hinge comprises four parts: the first part is a cylinder with a small cross-sectional area, which is connected to the threaded countersunk hole on the side wall of the vibration isolation connection platform; the second part is a regular square prism; the third part is a necked cylinder; and the fourth part is a cylinder with a threaded through hole, which is connected to the small regular square prism with a circular through hole at the front end of the amplitude transformer.

[0046] like Figure 4 As shown, the base platform is provided with several bolt holes for connecting to the vibration isolation object;

[0047] The accelerometers in the first to fourth vibration isolation modules collect vibration signals corresponding to the vibration source disturbance. These vibration signals are consistent with the vibration at the location of the vibration isolation module in terms of frequency and phase, and in terms of amplitude, the vibration signal and the intensity of the vibration at the location of the vibration isolation module are positively correlated. If the vibration signals generated by the accelerometers in the first to fourth vibration isolation modules all have the same amplitude, it means that the vibration-isolated object is in the longitudinal vibration mode; if any two of the vibration signals generated by the accelerometers in the first to fourth vibration isolation modules have a 180° phase difference, it indicates that the vibration-isolated object is in the bending vibration mode.

[0048] like Figure 5 As shown, the transducer in the vibration isolation module has two sets of dual-zone ceramic plates with a spatial phase difference of 90°, as well as stacked single-zone ceramic plates. Any two axially adjacent single-zone ceramic plates have opposite polarization directions, and any two radially adjacent dual-zone ceramic plates have opposite polarization directions. They are controlled by three channels, A, B, and C respectively. Channel A controls one set of dual-zone piezoelectric ceramic plates with the same phase, channel B controls another set of dual-zone piezoelectric ceramic plates with the same phase, and channel C controls all the single-zone ceramic plates. When the amplitude transformer in the vibration isolation module needs to... When there is bending vibration in the axial direction, an electrical signal is applied to channel A for excitation. When the amplitude transformer in the vibration isolation module needs... When there is bending vibration in the axial direction, an electrical signal is applied to channel B for excitation. When the amplitude transformer in the vibration isolation module needs... For longitudinal vibration in the axial direction, an electrical signal is applied to channel C for excitation; such as Figure 6 As shown, when an electrical signal is applied to channel A, a single amplitude transformer generates... Bending vibration in the axial direction;

[0049] like Figure 7 As shown, for longitudinal vibration, the principle of active vibration isolation in this invention is to apply an electrical signal to the B control channel of all vibration isolation units, causing the amplitude transformers of all vibration isolation units to generate local coordinate system... The axial bending vibration generated by the four vibration isolation modules is opposite in phase, consistent in frequency, and has the same amplitude as the vibration source. In other words, the vibration and the vibration source can cancel each other out, thus achieving the effect of vibration control.

[0050] like Figure 8 As shown, for bending vibration in the 45° direction of the XY plane, the principle of active vibration isolation in this invention is to apply an electrical signal to the B control channel of the first and third vibration isolation units, causing the amplitude transformers of these two vibration isolation units to generate... The axial bending vibration, generated by four vibration isolation modules, is opposite in phase, has the same frequency, and the same amplitude as the vibration source. This means the vibration and the vibration source can cancel each other out, achieving vibration control. Figure 9 As shown, for bending vibration in the 135° direction of the XY plane, an electrical signal is applied to the B control channel of the second and fourth vibration isolation units, causing the amplitude transformers of these two vibration isolation units to generate... The bending vibration in the axial direction achieves the effect of vibration control.

[0051] like Figure 10 As shown, for translation along the X-axis in the XY plane, the principle of active vibration isolation in this invention is to apply electrical signals to the C control channels of the first and third vibration isolation units, and to apply electrical signals to the A control channels of the second and fourth vibration isolation units, causing the amplitude transformers of the first and third vibration isolation units to generate... Longitudinal vibration in the axial direction is generated by the amplitude transformers of the second and fourth vibration isolation units. The longitudinal vibration in the axial direction, generated by the four vibration isolation modules, is opposite in phase, consistent in frequency, and has the same amplitude as the vibration source. In other words, the vibration and the vibration source can cancel each other out, thus achieving the effect of vibration control.

[0052] like Figure 11 As shown, the system acquires a feedforward signal characterizing the vibration state through a second accelerometer. This signal is input to the weight adjustment module for dynamic parameter optimization. After real-time processing, the controller generates a control command with specific phase characteristics, which forms an output signal to drive the piezoelectric actuator to produce mechanical action. The piezoelectric actuator outputs force onto the controlled object, and the first accelerometer collects the actual effect to form a feedback signal. This feedback signal carries the system's dynamic response characteristics and environmental interference information and is transmitted to the LMS algorithm module for error analysis. The LMS module calculates the weight correction amount through the gradient descent algorithm and continuously updates the filtering coefficients of the weight adjustment module. This process forms a closed-loop control loop, ensuring that the control action output by the piezoelectric actuator always maintains adaptive matching with the target vibration signal, ultimately achieving precise vibration cancellation.

[0053] like Figure 12As shown, the most significant feature of this invention lies in the twelve-channel control of the four vibration isolation modules. Each vibration isolation module has A, B, and C three-channel controls, which can control the bending vibration and axial longitudinal vibration of the amplitude transformer in both directions. Thus, based on the feedback signal, the twelve channels are controlled to perform vibration control on the vibration isolation connection platform. The control module also collects feedforward signals from the vibration source to predict and compensate for interference signals. The feedback signal is taken out from the system output and returned to the control module through four sensors for comparison with the set value. Through this control path, the control module can adjust its output according to the feedback signal to ensure that the system output matches the set value.

[0054] 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.

[0055] 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. A longitudinal bending composite six-degree-of-freedom piezoelectric active vibration isolation platform, the overall structure of which consists of a vibration isolation connection platform, a base platform, a control module, and first to fourth vibration isolation modules; The first to fourth vibration isolation modules have the same structure, each including a fixed base, a transducer base, a piezoelectric transducer, an amplitude transformer, a preload bolt, and a small flexible hinge; The fixed base has four threaded blind holes arranged in an array on its bottom surface and one of its side surfaces; the transducer base has a countersunk through hole at the center of its upper boss for the preload bolt to pass through; the base has five threaded blind holes of the same diameter and coaxiality with the side holes of the fixed base in its circumference and center; the piezoelectric transducer adopts a dual-unit composite structure, consisting of alternating layers of grounding electrode plates, square ceramic plates, and square electrode plates, wherein the front unit contains two sets of square piezoelectric ceramic plates with opposite polarization directions, and the rear unit is configured with two sets of spatially orthogonally distributed dual-zone ceramic plates. All ceramic plates are polarized along the thickness direction and adjacent ceramic plates have opposite polarization directions. Their outer contour matches the cross-section of the amplitude transformer base boss. The piezoelectric transducer has a through hole at its center for the preload bolt to pass through; the square electrode plate in the piezoelectric transducer has the same shape and cross-sectional area as the square ceramic plate. The square electrode plate is connected to the control module via a wire to receive control signals. This allows the vibration isolation module to generate the required longitudinal or bending vibration. The amplitude transformer adopts an irregular structure design, with the front end being a small square prism with a circular through hole to achieve bending constraint, and the rear end being a square prism with the same cross-sectional area as the front end through quarter-elliptical symmetrical cutting. Experiments have verified that when the elliptical surface shape coefficient is optimized to 0.08, the vibration transmission efficiency and stability of the amplitude transformer reach the best matching state. The two are integrally formed and threaded blind holes are set in the square prism. The pre-tightening bolt passes through the transducer base and the center hole of the piezoelectric transducer in sequence and is then threadedly connected to the amplitude transformer to form an axial prestress loading mechanism. The small flexible hinge consists of four parts: the first part is a cylinder with a small cross-sectional area, which is connected to the threaded countersunk hole on the side wall of the vibration isolation connection platform; the second part is a square prism; the third part is a necked cylinder; and the fourth part is a cylinder with a threaded through hole, which is connected to the small square prism with a circular through hole at the front end of the amplitude transformer. The first four accelerometers are respectively installed on the side wall of a small square prism with a circular through hole at the front end of the amplitude rod, away from the direction of the vibration isolation connection platform. All of them are triaxial sensors and are used to collect vibration feedback signals of the vibration isolation connection platform in the X-axis, Y-axis and Z-axis directions in the overall coordinate system. The second accelerometer is installed at the center of the base platform and is a triaxial sensor. It is used to collect vibration feedforward signals of the vibration source in the X-axis, Y-axis and Z-axis directions in the overall coordinate system. Both the vibration isolation connecting platform and the base platform are square flat plates. The vibration isolation connecting platform has four threaded through holes for connecting to the vibration isolation object. Each of the four sides of the vibration isolation connecting platform has a threaded countersunk hole near the corner of the platform, which is connected by a small flexible hinge. The base platform has four pairs of rounded corner grooves at symmetrical positions at one-third of the length of adjacent sides. The symmetrical distribution of these grooves can effectively avoid assembly misalignment or interference caused by processing errors. The bottom surface of the base platform is set as a flat mounting surface for connecting to the vibration source that needs to be fixed to the vibration isolation object. While ensuring structural stability, the tolerance characteristics of the grooves improve assembly adaptability. The four vibration isolation modules are arranged in a rectangular array on the surface of the base platform. The vibration isolation connecting platform is located at the geometric center of the four vibration isolation modules and is rigidly connected to the small flexible hinges of each module through the side wall. The square prism transition section in the small flexible hinge is coplanar with the side wall of the vibration isolation connecting platform. The fixed base of each vibration isolation module is fixed to the base platform through the bottom threaded hole. The threaded hole on its side and the corresponding hole of the transducer base form a coaxial assembly relationship. In the modular layout, the cross-sections of the upper bosses of the transducer bases in the first and third vibration isolation modules are parallel to each other. The cross-sections of the upper bosses of the transducer bases in the second and fourth vibration isolation modules are parallel to each other. The sides of the fixed bases of adjacent vibration isolation modules are arranged orthogonally. The bottom surface of all fixed bases is perpendicular to the base platform. The amplitude rod assembly realizes spatial vibration control through axial orthogonal configuration. The amplitude rods in two adjacent vibration isolation modules are axially perpendicular to each other. The amplitude rods of the diagonally distributed modules are axially parallel. The axes of all amplitude rods are orthogonal to the plane of their transducer bases. The control module is a controller, connected to the first and second accelerometers in the first to fourth vibration isolation modules, and further connected to the 12 channels that drive the vibration of the vibration isolation modules. The controller processes the feedback vibration signal from the first accelerometer and the feedforward vibration data from the second accelerometer in real time, dynamically adjusting the filter coefficients of each channel. Specifically, the controller automatically optimizes the control parameters of each drive channel by continuously comparing the minimum mean square error between the actual vibration response and the desired target value, using the gradient descent method to achieve precise phase compensation and amplitude adjustment of the output force of the drive components.

2. The longitudinal bending composite six-degree-of-freedom piezoelectric active vibration isolation platform according to claim 1 is characterized in that the vibration isolation connection platform is provided with a number of bolt holes, which can be used to connect with the vibration isolation object.

3. The working method of the longitudinal bending composite six-degree-of-freedom piezoelectric active vibration isolation platform according to claim 1, characterized in that it includes the following steps: For each of the first to fourth vibration isolation modules: Step 1) Collect vibration signals; install the first accelerometer on the vibration isolation connection platform to collect the platform vibration feedback signal in real time; install the second accelerometer on the base platform to collect the vibration source feedforward signal synchronously; the two sensors respectively acquire time-domain signals containing vibration frequency and amplitude, and transmit the dual signals synchronously to the control module to build the data input basis for closed-loop control; Step 2) Processing feedforward and feedback signals; The control module performs composite processing on the dual signals: First, it eliminates environmental noise and high-frequency clutter through a bandpass filter, and then performs phase reversal operation; The feedforward signal is used to predict the vibration transmission path, and the phase offset is corrected in real time through the feedback signal to generate a control signal with amplitude conservation and phase reversal characteristics. The controller realizes the fusion calculation of feedforward compensation and feedback correction to form an adaptive signal processing closed loop. Step 3) Iterative optimization of the driving signal: Establish a closed-loop iterative mechanism with residual vibration energy as the optimization target, continuously collect the residual vibration signal of the vibration isolation connection platform as a new feedback quantity, input it into the transverse filter to generate a reference signal; use the LMS algorithm to dynamically calculate the convolution value of the reference signal and the real-time residual signal, and adjust the filter weight coefficients step by step through the gradient descent method to complete the iterative optimization of the driving signal. Step 4) Output vibration control signal; distribute the processed control signal to the 12-channel drive array, monitor the residual disturbance signal after vibration control in real time, and send it back to the controller as the feedback input for the next control cycle, forming a complete closed-loop control chain of "signal acquisition-processing-execution-feedback"; taking the longitudinal vibration in the Z-axis direction of the overall coordinate system controlled by the vibration isolation module as an example, the control module sends a specific phase excitation voltage to the B channel of the four vibration isolation modules, triggering the piezoelectric transducer to generate a local coordinate system. Shaft bending vibration; after being amplified by the amplitude transformer, the vibration is converted into the reverse vibration wave of the Z-axis of the vibration isolation connection platform through the small flexible hinge mechanism, so as to achieve equal amplitude and opposite phase cancellation with the original vibration waveform. Through the above steps, the piezoelectric actuator is driven to generate a force that is precisely opposite in phase to the vibration source. Based on real-time vibration feedback data, the output phase and amplitude are dynamically adjusted so that the vibration energy in the target area is actively canceled and continuously attenuated, thereby reducing the vibration amplitude of the system.

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