A piezoelectric actuator-based active-passive vibration reduction device and a control method thereof

Abstract

A kind of piezoelectric actuator-based active and passive damping device and its control method, to solve the problem that existing multi-rotor unmanned aerial vehicle passive damping method is prone to resonance and damping performance is significantly affected by working condition, active damping method exists actuator stroke and energy consumption demand, sensitive to system model error and parameter drift, leading to multi-rotor unmanned aerial vehicle onboard camera still exists imaging blur.The upper platform of the device is connected with the unmanned aerial vehicle, the upper platform, the load platform, the piezoelectric actuator, the lower platform and the onboard imaging equipment are coaxial from top to bottom, the spring assembly is connected with the upper platform and the lower platform, the load platform is connected with the connector of the onboard imaging equipment through multiple connecting rods passing through the lower platform, and multiple spring assemblies and multiple connecting rods are distributed around the piezoelectric actuator.The method makes the piezoelectric actuator output reverse correction force according to the absolute acceleration of the device and the absolute acceleration of the load platform, and realizes damping in combination with the spring assembly.The application belongs to the field of damping technology.

Description

Technical Field

[0001] This invention relates to the field of vibration reduction technology, specifically to an active and passive vibration reduction device based on a piezoelectric actuator and its control method. Background Technology

[0002] Unmanned aerial vehicles (UAVs), with their advantages of maneuverability, rapid deployment, and controllable data acquisition costs, have become important platforms for information acquisition and damage detection, serving a wide range of fields. Compared with satellite remote sensing, UAVs can acquire data with higher spatial resolution and faster timeliness in lower airspaces, and can flexibly carry various types of sensors such as RGB, infrared, multispectral, and hyperspectral sensors according to mission requirements. The extraction of useful information largely depends on the quality of the images captured by the UAV. However, multi-rotor UAVs are affected by propeller or motor excitation, airframe structural modes, and aerodynamic disturbances during flight. The vibration energy covers a wide frequency range from low-frequency attitude jitter to mid-to-high-frequency structural vibrations, which can easily cause blurred images, video jitter, and loss of detail in airborne cameras, reducing the data quality for tasks such as remote sensing mapping, inspection, and target identification.

[0003] Current engineering practices often employ a combination of gimbal stabilization and passive vibration damping to improve the quality of data acquisition from airborne cameras. Gimbals are suitable for suppressing large-amplitude, low-frequency attitude disturbances, while passive vibration damping reduces the transmission of high-frequency, small-amplitude vibrations. However, traditional rubber and elastomer supports and spring-damper structures commonly used in UAV imaging platforms are prone to resonance amplification near their natural frequencies, and their vibration damping performance varies significantly with load, temperature, and excitation frequency. Relying solely on active vibration damping requires substantial actuator travel and energy consumption, and is highly sensitive to errors in the dynamic model and parameter drift of the vibration damping system. This results in persistent image blurring in multi-rotor UAV airborne cameras.

[0004] Piezoelectric actuators offer advantages such as fast response, large reverse correction force, and small size, making them suitable for small-amplitude, rapid compensation of UAV payloads. However, when a piezoelectric actuator is connected in parallel with an elastic element, the high stiffness of the piezoelectric actuator often dominates the system's equivalent stiffness, leading to an upward shift in the natural frequency. This causes passive vibration damping designs to fail and further increases the driving voltage and energy consumption requirements. Therefore, there is an urgent need for an active and passive vibration damping device that combines lightweight design, wide-frequency vibration reduction, and low-energy active compensation. Summary of the Invention

[0005] To address the problems of existing passive vibration reduction methods for multi-rotor UAVs being prone to resonance and having vibration reduction performance significantly affected by operating conditions, while active vibration reduction methods suffer from large actuator stroke and energy consumption requirements and are sensitive to system model errors and parameter drift, resulting in blurred images from the onboard camera of multi-rotor UAVs, this invention proposes an active and passive vibration reduction device based on piezoelectric actuators and its control method.

[0006] The technical solution adopted in this invention is:

[0007] An active and passive vibration damping device based on a piezoelectric actuator includes an upper platform, a load platform, a piezoelectric actuator, multiple sets of spring assemblies, a lower platform, and multiple connecting rods. The upper platform is fixedly connected to the UAV body or an airborne mounting base. The upper platform, load platform, and lower platform are coaxial and arranged parallel from top to bottom. The length and width of the upper platform and the lower platform are both greater than the length and width of the load platform. The two ends of the piezoelectric actuator are fixedly connected to the load platform and the lower platform, respectively, and the piezoelectric actuator is coaxial with the load platform and the lower platform. The two ends of each set of spring assemblies are fixedly connected to the upper platform and the lower platform, respectively, and multiple sets of spring assemblies are evenly distributed around the piezoelectric actuator. Multiple axially arranged connecting rods are evenly installed on the lower surface of the load platform. The multiple connecting rods are distributed around the piezoelectric actuator, and the other end of each connecting rod passes through the lower platform and is fixedly connected to the connecting parts of the airborne imaging equipment.

[0008] A control method for an active and passive vibration damping device based on a piezoelectric actuator includes the following steps:

[0009] S1. A first accelerometer is fixedly installed on the body of the UAV or the airborne mounting base connected to the upper platform, and a second accelerometer is fixedly installed on the connector of the airborne imaging equipment.

[0010] Based on the vibration transmitted to the active and passive vibration damping device during the flight of the UAV, the active and passive vibration damping device uses multiple sets of spring components for passive vibration damping. The remaining vibration after passive vibration damping is transmitted to the load platform. The absolute acceleration of the active and passive vibration damping device is obtained by the first acceleration sensor, and the absolute acceleration of the load platform is obtained by the second acceleration sensor.

[0011] S2. The absolute acceleration of the current active and passive vibration damping devices and the absolute acceleration of the current load platform are synchronously sent to the controller of the vibration damping system, and the controller outputs the drive voltage.

[0012] S3. In the piezoelectric drive channel of the vibration reduction system, the inverse model of the piezoelectric actuator hysteresis model is used as the feedforward compensator. The controller outputs the desired reverse correction force according to the vibration error. Based on the desired reverse correction force, the feedforward compensator is used to back-calculate the compensated drive voltage. The compensated drive voltage is input into the piezoelectric actuator for amplification. The amplified drive voltage is input into the piezoelectric actuator. The piezoelectric actuator outputs a reverse correction force consistent with the desired reverse correction force. The reverse correction force is transmitted along the axial direction of the piezoelectric actuator to the load platform and the lower platform, thus completing the active vibration reduction of the active and passive vibration reduction device.

[0013] The beneficial effects of this invention are as follows:

[0014] This invention utilizes a series connection between a piezoelectric actuator and a spring assembly to achieve passive vibration reduction, thereby lowering the driving voltage and energy consumption requirements. Active vibration reduction is achieved through the cooperation of the piezoelectric actuator and the load platform. The piezoelectric actuator is connected to both the load platform and the lower platform, reducing lateral stress and shear risk in the piezoelectric stack and improving long-term operational reliability. This invention improves the stability of airborne imaging equipment and effectively enhances the image acquisition quality of multi-rotor UAVs through both active and passive vibration reduction methods. This invention allows the passive structure to undertake the main vibration reduction task, while the active components only perform minor corrections to residual vibrations, thus reducing energy consumption and saturation risk, and improving the vibration reduction bandwidth and robustness.

[0015] This invention also solves the problems of limited payload redundancy and frequent changes in payload type for multi-rotor UAVs, as well as the problems of resonance and vibration reduction performance of UAVs being affected by operating conditions, by using lightweight structural materials and sectional design and connecting components to fix the load platform and airborne camera. It can be quickly integrated into airborne camera or sensor mounting systems.

[0016] The control method of the active and passive vibration reduction device of the present invention combines hysteresis inverse compensation and robust predictive control, which can maintain good vibration reduction performance under parameter drift and external disturbance changes, and can operate safely within voltage constraints. Attached Figure Description

[0017] Figure 1 This is a front view of the active and passive vibration damping device;

[0018] Figure 2 This is a cross-sectional view of a piezoelectric actuator;

[0019] Figure 3 This is a schematic diagram of the dynamic model of the active and passive vibration damping device;

[0020] Figure 4 This is a controller structure diagram;

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Upper platform; 2. Load platform; 3. Piezoelectric actuator; 4. Spring assembly; 5. Lower platform; 6. Connecting rod; 7. Threaded connector; 41. Upper spring fixing seat; 42. Lower spring fixing seat; 43. Spring; 31. Push rod; 32. Upper end cover; 33. Disc spring; 34. Piezoelectric stack; 35. Loading housing; 36. Preload screw; 37. Lower end cover. Detailed Implementation

[0023] Specific implementation method one: Combining Figures 1-2This embodiment describes an active and passive vibration damping device based on a piezoelectric actuator, used to improve the stability of an unmanned aerial vehicle (UAV) imaging device (airborne camera), enabling the airborne camera to obtain clear images. It includes an upper platform 1, a load platform 2, a piezoelectric actuator 3, multiple spring assemblies 4, a lower platform 5, multiple connecting rods 6, and multiple threaded connectors 7.

[0024] The threaded connector 7 includes bolts, screws, studs, or rigid hardware with external threads and nuts. The upper platform 1 is fixedly connected to the UAV body or airborne mounting base. The upper platform 1, load platform 2, and lower platform 5 are coaxial and parallel from top to bottom. The length and width of the upper platform 1 and the lower platform 5 are both greater than the length and width of the load platform 2. In this invention, the upper platform 1 and lower platform 5 have the same length, width, and height. The two ends of the piezoelectric actuator 3 are fixedly connected to the load platform 2 and lower platform 5 respectively, and the piezoelectric actuator 3 is coaxial with the load platform 2 and lower platform 5. The two ends of each spring assembly 4 are fixedly connected to the upper platform 1 and lower platform 5 respectively, and multiple spring assemblies 4 are evenly distributed around the piezoelectric actuator 3. In this invention, four spring assemblies 4 and four connecting rods 6 are provided. The four spring assemblies 4 are located in front, behind, left, and right of the piezoelectric actuator 3 respectively. The four connecting rods 6 are arranged in a rectangular pattern around the piezoelectric actuator 3. Spring 43 is made of low-stiffness material, specifically stainless steel in this invention. Each spring assembly 4 primarily bears the load weight and provides vertical flexibility, achieving passive vibration reduction for the active and passive vibration damping device. Spring 43 is designed to always be in a stretched state, ensuring it operates within tension or near-linear range during operation. This reduces the impact of geometric nonlinearity caused by the spring 43's installation geometry and large deformation on vibration reduction performance. Through a matching design between the spring 43's stiffness and the device's equivalent mass, this invention ensures the vibration reduction system's natural frequency avoids the main excitation frequency band of the UAV, entering the vibration reduction range to reduce transmissivity. The four-point symmetrical arrangement of the four spring assemblies 4 helps reduce imaging axis offset caused by pitch and roll coupling of the airborne camera. Multiple axially arranged connecting rods 6 are evenly installed on the lower surface of the load platform 2, distributed around the piezoelectric actuator 3. The other end of each connecting rod 6 passes through the lower platform 5 and is fixedly connected to the connecting parts of the airborne imaging equipment. Vibration is passively isolated by spring assembly 4 and then transmitted to load platform 2 and piezoelectric actuator 3. Piezoelectric actuator 3 outputs a reverse correction force that acts on load platform 2, thereby reducing the vibration of the airborne imaging equipment and improving its stability. The series force transmission method between load platform 2 and spring assembly 4 avoids the upward shift of equivalent stiffness caused by parallel connection, ensuring the effectiveness of the passive vibration reduction parameter design.

[0025] Multiple first through holes and multiple second through holes are vertically machined on the upper platform 1. These holes are evenly distributed around the central axis of the upper platform 1, with the second through holes located outside the first through holes. Both the first and second through holes are either conventional through holes or threaded through holes, and are located outside the position of the load platform 2. A portion of the threaded connectors 7 pass through each of the first through holes to fix the upper platform 1 to the UAV body or airborne mounting base. The remaining threaded connectors 7 pass through each of the second through holes to fix each set of spring assemblies 4 to the upper platform 1.

[0026] In this invention, four columns are evenly arranged on the lower surface of the load platform 2, and the four columns and the load platform 2 can be integrated as one piece. A threaded hole or a through hole is machined at the center point of the lower surface of each column. When a threaded hole is used, each connecting rod 6 can be bolted, so that the connecting rod 6 and the threaded hole of the column can be connected by thread; when a through hole is used, each connecting rod 6 and the through hole of the column can be installed by adhesive.

[0027] The piezoelectric actuator 3 includes a push rod 31, an upper end cover 32, a disc spring 33, a piezoelectric stack 34, a loading housing 35, a preload screw 36, and a lower end cover 37. In this invention, the loading housing 35 is a hollow cylindrical shell structure with a rigid structure for limiting movement. The cooperation between the loading housing 35 and the preload screw 36 ensures that the piezoelectric stack is under pressure under all operating conditions, and the ball joint at the end of the push rod 31 absorbs assembly errors and reduces the lateral stress and shear risk of the piezoelectric stack. The upper end cover 32 and the lower end cover 37 are respectively installed at the upper and lower ends of the loading housing 35. A third through hole is machined at the center of the upper end cover 32, and a first screw hole is machined at the center of the upper surface of the lower end cover 37. The push rod 31 has an inverted T-shaped structure. An arc groove is machined at the center of the horizontal end of the inverted T. The vertical end of the inverted T passes through the third through hole of the upper end cover 32 and connects to the lower surface of the load platform 2. The horizontal end of the inverted T is installed inside the loading housing 35, and a disc spring 33 is provided between the horizontal end of the inverted T and the upper end cover 32. A piezoelectric stack 34 is provided between the horizontal end of the inverted T and the lower end cover 37. The head end of the piezoelectric stack 34 and the arc groove machined at the horizontal end of the inverted T form a ball head connection. The preload screw 36 passes through the lower platform 5 and is installed in the first screw hole.

[0028] Each spring assembly 4 includes a spring fixing upper seat 41, a spring fixing lower seat 42, and a spring 43. The two ends of the spring 43 are fixedly connected to the spring fixing upper seat 41 and the spring fixing lower seat 42, respectively. A fourth through hole is machined at the center of the spring fixing upper seat 41. Each threaded connector 7 passes through the fourth through hole and the second through hole to fix the spring fixing upper seat 41 to the upper platform 1. The spring fixing lower seat 42 is fixedly connected to the upper surface of the lower platform 5. In this invention, the spring fixing lower seat 42 and the lower platform 5 are connected by bolts and nuts.

[0029] A fifth through hole is machined at the center of the lower platform 5, and multiple sixth through holes are evenly machined around the fifth through hole. The positions of the multiple sixth through holes correspond to the positions of the connecting rods 6 on the lower surface of the load platform 2. Each connecting rod 6 on the lower surface of the load platform 2 passes through each sixth through hole and is fixedly connected to the connecting piece of the airborne imaging device. The pre-tightening screw 36 passes through the fifth through hole and is installed in the first screw hole of the lower end cover 37. In this invention, the load platform 2 and the connecting piece of the airborne camera are connected by bolts and nuts, that is, the connecting rod 6 is a bolt.

[0030] The active and passive vibration damping device of the present invention is manufactured using lightweight 3D printing materials, and thick walls and transition fillets are set in key stress parts to achieve a balance between lightweight and strength. The total mass of the device is reduced while meeting the requirements of strength and stiffness, thus meeting the stringent load requirements of UAVs.

[0031] Specific Implementation Method Two: Based on the active and passive vibration damping device based on a piezoelectric actuator proposed in Specific Implementation Method One, this implementation method differs from Specific Implementation Method Two in that the control method of the active and passive vibration damping device based on a piezoelectric actuator includes the following steps:

[0032] S1. A first accelerometer is fixedly installed on the UAV body or airborne mounting base connected to the upper platform 1, and a second accelerometer is fixedly installed on the connector of the airborne imaging equipment.

[0033] Based on the vibration transmitted to the airborne imaging equipment and active and passive vibration damping devices during normal flight of the UAV, the active and passive vibration damping devices are first passively damped by four sets of spring assemblies 4, that is, physically damped. The remaining vibration after passive damping is transmitted to the load platform 2. Then, the absolute acceleration of the active and passive vibration damping devices is obtained by the first acceleration sensor, and the absolute acceleration of the load platform 2 is obtained by the second acceleration sensor.

[0034] S2, such as Figure 3 As shown, the direction from the lower platform 5 to the upper platform 1 is defined as the positive direction. The vertical absolute displacement of the UAV body or airborne mounting base connected to the upper platform 1 is defined as... The mass of the middle section of the active and passive vibration damping device is defined as... The vertical absolute displacement of the middle part is The middle part of the active and passive vibration damping device includes a piezoelectric actuator 3 and a lower platform 5. The mass of the load on the active and passive vibration damping device is defined as... and the vertical absolute displacement of the load is The load of the active and passive vibration damping device includes a load platform 2, an airborne camera, and the connecting parts of the airborne camera.

[0035] Based on the above definition, the active and passive vibration damping device is modeled using Newton's second law, yielding an analytical solution for the vibration transmissibility of the active and passive vibration damping device and its dynamic model. This dynamic model is a continuous-time theoretical dynamic model.

[0036] (1)

[0037] in, For the quality matrix, , This represents the absolute motion vector of each platform (upper platform 1, load platform 2, lower platform 5). for The second derivative, Here is the stiffness matrix. , For the damping of spring 43, For the damping of piezoelectric actuator 3, for The first derivative, Here is the damping matrix. , Let be the stiffness of spring 43. The equivalent stiffness of piezoelectric actuator 3 is given by [reference to stiffness]. , , for The first derivative, This is a matrix describing the direction of the reverse correction force output by piezoelectric actuator 3. , This is the reverse correction force output by piezoelectric actuator 3.

[0038] S3. In the piezoelectric drive channel (i.e., the process before voltage is transmitted to the piezoelectric actuator) composed of the controller and piezoelectric actuator of the vibration reduction system, the inverse model of the piezoelectric actuator hysteresis model is introduced as a feedforward compensator. The controller outputs the desired reverse correction force according to the vibration error. Based on the desired reverse correction force, the feedforward compensator is used to back-calculate the compensated drive voltage. The compensated drive voltage is input into the piezoelectric actuator for amplification. The amplified drive voltage is then input into piezoelectric actuator 3. Piezoelectric actuator 3 outputs a reverse correction force consistent with the desired reverse correction force. Thus, the approximate relationship between the drive voltage (input) and the reverse correction force (output) of piezoelectric actuator 3 can be obtained:

[0039] (2)

[0040] in, for The reverse correction force output by piezoelectric actuator 3 at all times These are the linearization coefficients. for The constant driving voltage input to piezoelectric actuator 3.

[0041] S4. Based on S1, set the acceleration sampling period to... The absolute acceleration of the current active and passive vibration damping devices and the absolute acceleration of the current load platform 2 are synchronously sampled and sent to the controller of the vibration damping system. The controller outputs a drive voltage. The specific process is as follows:

[0042] S41. External disturbances exist during UAV flight, such as excitation from propeller and motor rotation, modal vibration of the airframe, and aerodynamic disturbances. Considering long-term use, the model mismatch caused by factors such as spring stiffness and damping, load mass, and voltage-force mapping error of the piezoelectric actuator 3, this invention combines model mismatch and external disturbances in the actual vibration reduction system into an additive output disturbance. .

[0043] S42, such as Figure 4 As shown, the absolute acceleration of the current active and passive vibration damping devices and the absolute acceleration of the current load platform 2 are synchronously sent to the controller of the vibration damping system. The controller outputs a drive voltage. The specific process is as follows:

[0044] (1) The absolute acceleration of the current active and passive vibration damping devices is numerically integrated. During the integration process, bandpass filtering is used to suppress integration drift, and the data is updated at each sampling time. The displacement and velocity of the UAV body or airborne mounting base connected to the upper platform 1 are obtained, and the displacement and velocity are used as a measurable disturbance vector:

[0045] (3)

[0046] in, for The measurable perturbation vector at time . for The displacement of the drone body or airborne mounting base connected to the upper platform 1 at all times. for The first derivative is expressed as The speed of the drone body or airborne mounting base connected to the upper platform 1 at all times. This indicates transpose.

[0047] Define the state variables of the vibration reduction system at the same moment as the measurable disturbance vector as:

[0048] (4)

[0049] in, for The state variables of the vibration damping system at all times Middle part of active and passive vibration damping device Displacement at any moment Load of main and passive vibration damping devices Displacement at any moment for The first derivative, for The first derivative, This indicates transpose.

[0050] Based on the dynamic model of S2, the approximate relationship between the driving voltage and the reverse correction force of S3, the measurable disturbance vector, and the state variables, a discrete state-space model of the active and passive vibration damping device is established:

[0051] (5)

[0052] (6)

[0053] in, This represents the sequence number of the discrete sampling time. For the vibration reduction system at discrete times State variables, For the vibration reduction system at discrete times State variables, For the vibration reduction system at discrete times The driving voltage, For the vibration reduction system at discrete times Measurable disturbances , Discrete time The displacement of the UAV body or airborne mounting base connected to the upper platform 1 at that time. for The first derivative is expressed as the discrete time... The speed of the drone body or airborne mounting base connected to the upper platform 1 For the vibration reduction system at discrete times The absolute acceleration of the load platform 2 , , , , The discrete state space matrix is:

[0054] (7)

[0055] (8)

[0056] (9)

[0057] (10)

[0058] (11)

[0059] The discrete state-space model is used to characterize the correspondence between the state variables, driving voltage, measurable disturbance and absolute acceleration of the load platform 2 under discrete sampling conditions of the active and passive vibration damping device.

[0060] (2) The present invention uses a sliding mode perturbation observer to estimate the output additive perturbation online. The process is as follows:

[0061] Based on the discrete state-space model of active and passive vibration reduction devices, the output of the sliding mode disturbance observer is defined. With error They are respectively:

[0062] (12)

[0063] (13)

[0064] in, The vibration reduction system output by the sliding mode disturbance observer at discrete times The estimated absolute acceleration of load platform 2, It is a known quantity, directly output by the sliding mode perturbation observer. For the vibration reduction system at discrete times The output additive perturbation estimate, For the vibration reduction system at discrete times The following includes State variable estimates at time, , Discrete moments in the middle section of the active and passive vibration damping device displacement, Load discrete moments of active and passive vibration damping devices displacement, for The first derivative, for The first derivative, This indicates transpose. This is the error.

[0065] The sliding mode perturbation observer can then take the following discrete update law, resulting in the following expression for the sliding mode perturbation observer:

[0066] (14)

[0067] (15)

[0068] in, For the vibration reduction system at discrete times The following includes State variable estimates at time, For linear observation gain, For the vibration reduction system at discrete times The output additive perturbation estimate, For the gain estimation of the disturbance, given a value, , Boundary layer thickness, This is used to suppress chattering. This represents a saturation function.

[0069] Under the assumption of slow variation in perturbation, the prediction window of the sliding mode perturbation observer can take... .

[0070] At each sampling time, the absolute acceleration of the load platform 2 obtained by S1 is... The driving voltage applied to the vibration reduction system and the measurable disturbance input to the sliding mode disturbance observer will output an estimate of the absolute acceleration of the load platform 2. According to equation (13), we get According to the calculations in equations (12)-(15), using Update and get Based on the absolute acceleration of load platform 2 obtained from S1 and The difference is used to obtain the corrected absolute acceleration value of load platform 2. :

[0071] (16)

[0072] (3) The present invention uses a model predictive controller to predict the driving voltage, specifically:

[0073] The model predictive controller uses the discrete state-space model of the active and passive vibration damping devices as the prediction model. The prediction step size of the model predictive controller is set to... and control step size Define the reference output of the model predictive controller as This means that the absolute acceleration of the load approaches zero. Simultaneously, piezoelectric actuator amplitude and rate of change constraints are applied to the model predictive controller. A quadratic programming (QP) problem is constructed based on the discrete state-space model and the amplitude and rate of change constraints.

[0074] At each sampling time, the prediction model is based on The measurable disturbance obtained by S42, combined with the aforementioned preset conditions, yields a set of driving voltage sequences that make the absolute acceleration of load platform 2 closer to the target value. Then, using a rolling time-domain strategy, only the first driving voltage corresponding to the current sampling moment in the driving voltage sequence is output. This enables the model predictive controller to... Closed-loop regulation is performed, and a QP is constructed based on this to solve for the driving voltage at the current sampling time, which improves the robustness of the model predictive controller to disturbances and parameter changes.

[0075] Based on predicted driving voltage and prediction step size Control step size Absolute acceleration of load platform 2 And the reference output of the model predictive controller, construct the rolling optimization cost function of the model predictive controller. :

[0076] (17)

[0077] in, To output weights, , To control the weights, , This indicates transpose.

[0078] To enhance closed-loop robustness, this invention utilizes a sliding mode disturbance observer combined with a model predictive controller to implement a robust model predictive control (RMPC) strategy. The controller of the vibration reduction system is defined as including a sliding mode disturbance observer (SMO) and a model predictive controller (MPC).

[0079] S5. Based on S3, a feedforward compensator is used to compensate the driving voltage. The compensated driving voltage is then amplified by inputting it into the piezoelectric actuator. The amplified driving voltage is then input into the piezoelectric actuator 3, which outputs a reverse correction force, generating a corresponding axial extension. Since the two ends of the piezoelectric actuator 3 are connected to the load platform 2 and the lower platform 5 respectively, the reverse correction force is transmitted along the axial direction of the piezoelectric actuator 3 to the load platform 2 and the lower platform 5, thereby improving the stability of the load platform 2 and the airborne imaging equipment, reducing the vibration response of the load platform 2 and the airborne imaging equipment, and achieving active vibration reduction.

[0080] This invention employs a hybrid approach of active vibration damping and passive vibration damping via spring 43, achieving continuous vibration reduction during multi-rotor UAV flight through repeated execution of both active and passive damping. The invention uses a model predictive controller to predict the changes in the reverse correction force output by the piezoelectric actuator 3 under different driving voltages over several future sampling times, thereby actively compensating for the residual vibration of the load platform 2. The active and passive vibration damping devices and their control methods can be used for optoelectronic payload mounting interfaces on multi-rotor UAVs and other lightweight platforms, and can also be extended to vibration reduction and stabilization of multi-sensor payloads.

[0081] This invention may have other embodiments. Without departing from the spirit and essence of this invention, those skilled in the art can make various corresponding changes and modifications according to this invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. An active and passive vibration damping device based on a piezoelectric actuator, characterized in that: It includes an upper platform (1), a load platform (2), a piezoelectric actuator (3), multiple spring assemblies (4), a lower platform (5), and multiple connecting rods (6). The upper platform (1) is fixedly connected to the UAV body or an airborne mounting base. The upper platform (1), the load platform (2), and the lower platform (5) are coaxial and arranged parallel from top to bottom. The length and width of the upper platform (1) and the lower platform (5) are both greater than the length and width of the load platform (2). The two ends of the piezoelectric actuator (3) are fixedly connected to the load platform (2) and the lower platform (5) respectively. The piezoelectric actuator (3) is fixedly connected to the load platform (2) and the lower platform (5). The two ends of each spring assembly (4) are fixedly connected to the upper platform (1) and the lower platform (5) respectively. Multiple spring assemblies (4) are evenly distributed around the piezoelectric actuator (3). Multiple axially arranged connecting rods (6) are evenly installed on the lower surface of the load platform (2). Multiple connecting rods (6) are distributed around the piezoelectric actuator (3). The other end of each connecting rod (6) passes through the lower platform (5) and is fixedly connected to the connecting parts of the airborne imaging equipment. It also includes the control method for the active and passive vibration damping devices, the specific steps of which are as follows: S1. A first acceleration sensor is fixedly installed on the UAV body or airborne mounting base connected to the upper platform (1), and a second acceleration sensor is fixedly installed on the connector of the airborne imaging equipment. According to the vibration transmitted to the active and passive vibration damping device during the flight of the UAV, the active and passive vibration damping device uses multiple sets of spring components (4) to perform passive vibration damping. The remaining vibration after passive vibration damping is transmitted to the load platform (2). The absolute acceleration of the active and passive vibration damping device is obtained by the first acceleration sensor, and the absolute acceleration of the load platform (2) is obtained by the second acceleration sensor. S2. The absolute acceleration of the current active and passive vibration damping devices and the absolute acceleration of the current load platform (2) are synchronously sent to the controller of the vibration damping system. The controller outputs the drive voltage. The specific process is as follows: S21. Numerically integrate the absolute acceleration of the current active and passive vibration damping devices, and use bandpass filtering to suppress integration drift during the integration process to obtain measurable disturbance. S22. Input the measurable disturbance, the absolute acceleration of the current load platform (2) and the driving voltage applied to the vibration reduction system into the sliding mode disturbance observer. The sliding mode disturbance observer outputs the current time-incremental disturbance. The output additive disturbance includes model mismatch and external interference in the actual vibration reduction system. The sliding mode disturbance observer is: （1） （2） （3） （4） （5） in, This represents the sequence number of the discrete sampling time. For the vibration reduction system at discrete times The following includes State variable estimates at time, , Discrete moments in the middle section of the active and passive vibration damping device displacement, Load discrete moments of active and passive vibration damping devices displacement, for The first derivative, for The first derivative, Indicates transpose. For the vibration reduction system at discrete times The following includes State variable estimates at time, , , , , Both are discrete state-space matrices. For the vibration reduction system at discrete times The driving voltage, For the vibration reduction system at discrete times Measurable disturbances For linear observation gain, For error, For the vibration reduction system at discrete times The output additive perturbation estimate, For the vibration reduction system at discrete times The output additive perturbation estimate, To estimate the gain for the perturbation, , Boundary layer thickness, , Represents the saturation function. For the vibration reduction system at discrete times The absolute acceleration of the load platform (2) The vibration reduction system obtained by the sliding mode perturbation observer at discrete time intervals The absolute acceleration estimate of the load platform (2) Discrete time The displacement of the UAV body or airborne mounting base connected to the upper platform (1) at that time, for The first derivative is expressed as the discrete time... The speed of the UAV body or airborne mounting base connected to the upper platform (1); S23. The difference between the absolute acceleration of the current load platform (2) and the output additive disturbance is used as the corrected absolute acceleration value of the current load platform (2). ; S24. The absolute acceleration value of the current load platform (2) is corrected. The measurable disturbance input model predictive controller obtained from S21 outputs a driving voltage sequence, and adopts a rolling time-domain strategy to output only the first driving voltage from the driving voltage sequence; The model predictive controller uses the discrete state-space model of the active and passive vibration damping devices as the prediction model, and sets the prediction step size of the model predictive controller to be... and control step size Define the reference output of the model predictive controller as That is, the absolute acceleration of the load approaches 0, and the piezoelectric actuator (3) amplitude and rate of change constraint is applied to the model predictive controller; The discrete state-space model of the active and passive vibration damping device is as follows: （6） （7） in, For the vibration reduction system at discrete times State variables, For the vibration reduction system at discrete times State variables; S3. In the piezoelectric drive channel of the vibration reduction system, the inverse model of the hysteresis model of the piezoelectric actuator (3) is used as the feedforward compensator. The controller outputs the desired reverse correction force according to the vibration error. According to the desired reverse correction force, the feedforward compensator is used to calculate the compensated drive voltage. The compensated drive voltage is input into the piezoelectric driver for amplification. The amplified drive voltage is input into the piezoelectric actuator (3). The piezoelectric actuator (3) outputs the reverse correction force consistent with the desired reverse correction force. The reverse correction force is transmitted along the axial direction of the piezoelectric actuator (3) to the load platform (2) and the lower platform (5) to complete the active vibration reduction of the active and passive vibration reduction device. The relationship between the input driving voltage and the output reverse correction force of the piezoelectric actuator (3) is as follows: （8） in, for The reverse correction force output by the piezoelectric actuator (3) at all times, These are the linearization coefficients. for The driving voltage input to the piezoelectric actuator (3) at any time.

2. The active and passive vibration damping device based on a piezoelectric actuator according to claim 1, characterized in that: It also includes multiple threaded connectors (7), which are bolts or screws.

3. The active and passive vibration damping device based on a piezoelectric actuator according to claim 2, characterized in that: The upper platform (1) is vertically machined with multiple first through holes and multiple second through holes. The multiple first through holes and multiple second through holes are evenly distributed around the central axis of the upper platform (1). The multiple second through holes are located outside the multiple first through holes. Some threaded connectors pass through the first through holes to fix the upper platform (1) to the UAV body or airborne mounting base. Other threaded connectors pass through the second through holes to fix the spring assembly (4) to the upper platform (1).

4. The active and passive vibration damping device based on a piezoelectric actuator according to claim 3, characterized in that: The piezoelectric actuator (3) includes a push rod (31), an upper end cover (32), a disc spring (33), a piezoelectric stack (34), a loading housing (35), a preload screw (36), and a lower end cover (37). The upper end cover (32) and the lower end cover (37) are respectively installed at the upper and lower ends of the loading housing (35). A third through hole is machined at the center of the upper end cover (32), and a first screw hole is machined at the center of the upper surface of the lower end cover (37). The push rod (31) has an inverted T-shaped structure, with the horizontal end of the inverted T... An arc-shaped groove is machined at the center. The vertical end of the inverted T passes through the third through hole of the upper end cover (32) and connects to the lower surface of the load platform (2). The horizontal end of the inverted T is installed inside the loading housing (35), and a disc spring (33) is provided between the horizontal end of the inverted T and the upper end cover (32). A piezoelectric stack (34) is provided between the horizontal end of the inverted T and the lower end cover (37). The head end of the piezoelectric stack (34) and the arc-shaped groove form a ball head connection. The preload screw (36) passes through the lower platform (5) and is installed in the first screw hole.

5. The active and passive vibration damping device based on a piezoelectric actuator according to claim 4, characterized in that: Each spring assembly (4) includes a spring fixing upper seat (41), a spring fixing lower seat (42) and a spring (43). The two ends of the spring (43) are fixedly connected to the spring fixing upper seat (41) and the spring fixing lower seat (42) respectively. A fourth through hole is machined at the center of the spring fixing upper seat (41). Each threaded connector (7) passes through the fourth through hole and the second through hole to fix the spring fixing upper seat (41) to the upper platform (1). The spring fixing lower seat (42) is fixedly connected to the upper surface of the lower platform (5).

6. The active and passive vibration damping device based on a piezoelectric actuator according to claim 5, characterized in that: The lower platform (5) has a fifth through hole machined in the center, and a number of sixth through holes are machined evenly around the fifth through hole. Each connecting rod (6) passes through each sixth through hole and is fixedly connected to the connecting piece of the airborne imaging device. The pre-tightening screw (36) passes through the fifth through hole and is installed in the first screw hole.

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