Wide-amplitude vibration suppression system for truss structure

Abstract

The invention relates to a wide-amplitude vibration suppression system for a truss structure. The wide-amplitude vibration suppression system comprises a vibration measurement subsystem, an axial inhaul cable subsystem, a piezoelectric subsystem and a control system. The vibration measurement subsystem measures the vibration condition of the truss structure in real time and feeds back the vibration condition to the control system; the piezoelectric subsystem is embedded into the truss structure and generates real-time displacement according to piezoelectric control signals of the control system; the axial inhaul cable subsystem comprises an inhaul cable, a tension executing mechanism and a tension measurement feedback mechanism; the control system is used for determining the working states of the axial inhaul cable subsystem and the piezoelectric subsystem; pID (Proportion Integration Differentiation) control is adopted, and a control signal is generated and sent to the piezoelectric subsystem or the axial inhaul cable subsystem. The problem that a traditional control method is difficult to consider can be solved.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft structural vibration control and relates to a wide-amplitude vibration suppression system for truss structures based on axial cable-piezoelectric composite action. It is mainly applied to high-precision spacecraft platforms and is particularly suitable for solving wide-band (0.01-500Hz) and wide-amplitude (10um-10mm) composite vibration problems caused by attitude and orbit control system disturbances, solar array drive mechanism motion, and flywheel component micro-vibration during on-orbit operation. Background Technology

[0002] As spacecraft evolve towards ultra-high precision and ultra-stable platforms, structural vibration control faces unprecedented technical challenges. Modern high-resolution optical payloads require platform angular stability to reach the sub-microradian level (<1μrad), corresponding to allowable structural vibration amplitudes that often need to be controlled at the micrometer level (<10μm). However, the on-orbit operating environment of spacecraft contains multiple vibration sources: low-frequency, large-amplitude disturbances (such as solar array deployment impacts and 0.1-10Hz, 1-10mm vibrations caused by attitude control thruster ignition) and high-frequency micro-vibrations (such as 10-500Hz, 10-100µm vibrations caused by reaction wheels and refrigerators). In the field of vibration suppression for spacecraft truss structures, existing technologies typically employ two methods to address the wide-bandwidth, wide-amplitude vibrations induced by multiple disturbance sources during on-orbit operation: passive vibration isolation and active control.

[0003] Passive vibration isolation technology, such as the use of dampers or viscoelastic materials, can effectively suppress vibrations in specific frequency bands to a certain extent by dissipating energy, and has the advantages of simple structure and no need for external energy. However, its dynamic parameters are fixed and it is difficult to adaptively adjust them according to the actual vibration environment. Its suppression effect on broadband vibrations, especially the combined excitation of low and high frequencies, is limited, and its damping characteristics are prone to change in microgravity environments, which limits its application potential in ultra-high precision spacecraft.

[0004] While active control methods possess adaptive adjustment capabilities, their engineering implementation on truss structures faces significant challenges due to the harshness of the on-orbit environment. Since truss vibrations are predominantly bending modes, active control requires the application of a main force perpendicular to the truss axis, making actuator placement in orbit extremely difficult. Furthermore, existing active control methods generally suffer from response lag, insufficient sensitivity to minute signals, and control dead zones, restricting their engineering application in spacecraft.

[0005] Therefore, although existing methods are effective to some extent in specific scenarios, there is still a lack of an efficient suppression method that can simultaneously cover the entire wide amplitude range from quasi-static deformation to high-frequency micro-vibrations. Developing a composite control strategy that can simultaneously suppress a wide amplitude of vibrations while ensuring system reliability and aerospace applicability has become a significant challenge in high-precision spacecraft structural design. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a wide-amplitude vibration suppression system for truss structures based on axial cable-piezoelectric composite action. It can suppress vibrations in the combined case of low-frequency large-amplitude deformation (1-10mm amplitude) and high-frequency small-amplitude vibration (10-100um amplitude), solving the problem that traditional control methods cannot take into account both.

[0007] The solution of the present invention is: A wide-amplitude vibration suppression system for truss structures includes a vibration measurement subsystem, an axial cable subsystem, a piezoelectric system, and a control system. Vibration measurement subsystem: measures the vibration of the truss structure in real time and feeds it back to the control system; Piezoelectric system: Embedded in the truss structure, it generates real-time displacement based on the piezoelectric control signal from the control system; Axial cable subsystem: includes cables, tension actuators, and tension measurement feedback mechanisms; the cables are arranged along the truss axis, the tension measurement feedback mechanism detects the tension value in the cables in real time and feeds it back to the control system, and the tension actuator applies tension to the cables according to the drive control signal of the control system; Control system: Based on the feedback information from the vibration measurement subsystem, the current vibration status of the truss structure is determined, and the working status of the axial cable subsystem and the piezoelectric system is determined. PID control is adopted. When the piezoelectric system is working, a piezoelectric control signal is generated based on the feedback information from the vibration measurement subsystem and sent to the piezoelectric system. When the axial cable subsystem is working, a drive control signal is generated based on the feedback information from the vibration measurement subsystem and the feedback information from the tension measurement feedback mechanism and sent to the axial cable subsystem.

[0008] Preferably, the piezoelectric system is a piezoelectric material actuator, which includes a set of piezoelectric ceramic modules and a housing assembly. The set of piezoelectric ceramic modules are stacked and placed inside the housing assembly, and the size of the housing assembly matches the size of the stacked piezoelectric ceramic modules.

[0009] Preferably, the tension actuator includes, but is not limited to, a linear motor, a joint motor, or a voice coil motor.

[0010] Preferably, the tension measurement feedback mechanism includes, but is not limited to, tension / compression sensors, spring force measuring mechanisms, and piezoelectric strain sensors.

[0011] Preferably, the cable is made of a high-modulus material, with an axial modulus of not less than 30 GPa when tensioned.

[0012] Preferably, the control system determines the current vibration status of the truss structure based on feedback information from the vibration measurement subsystem, and determines the operating status of the axial cable subsystem and the piezoelectric system, as follows: Preset displacement criterion values A ; The current vibration amplitude of the truss structure is determined based on the feedback information from the vibration measurement subsystem. If the vibration amplitude is ≤ A At this time, the piezoelectric system is activated and the axial cable subsystem is deactivated; When the vibration amplitude is > A At this time, the axial cable subsystem is activated and the piezoelectric system is deactivated.

[0013] Preferably, the control quantity input by the control system to the piezoelectronic system satisfy:

[0014] in This represents the control parameter matrix in the state-space equations of the truss structure. This is the solution to the Riccati equation corresponding to the state-space equations of the truss structure. and These are the vibration displacement and velocity calculated based on feedback information from the vibration measurement subsystem. It is a state-space vector formed by splicing vibration displacement and velocity.

[0015] Preferably, the control quantity input by the control system to the axial cable subsystem satisfy:

[0016] and These are the vibration displacement and velocity calculated based on feedback information from the vibration measurement subsystem. This is the stiffness variation matrix of the truss structure when the axial cables are tightened and relaxed. It is a symbolic function.

[0017] The advantages of this invention compared to the prior art are: (1) Achieved composite vibration suppression with wide amplitude and wide frequency band: The present invention innovatively combines the axial cable subsystem and the piezoelectronic system, and takes advantage of their respective advantages in large stroke, high load-bearing capacity and high precision and fast response. It overcomes the limitations of single actuation mode in amplitude or frequency band coverage, and can suppress vibration with a wide amplitude of 10um-10mm in an integrated manner, which significantly improves the adaptability of spacecraft truss structure to complex on-orbit vibration environment.

[0018] (2) High system integration, suitable for aerospace application scenarios: By reusing embedded piezoelectric actuation with existing axial cables, the addition of large external structures is avoided. While achieving wide amplitude vibration suppression, the system is lightweight, highly reliable and engineering feasible. It is especially suitable for spacecraft platforms with strict constraints on weight, space and reliability. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an embodiment of the wide-amplitude vibration suppression system for truss structures according to the present invention; Figure 2 This is a schematic diagram of the axial cable subsystem and the piezoelectric system of the present invention. Detailed Implementation

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] This invention relates to a wide-amplitude vibration suppression system for truss structures based on axial cable-piezoelectric composite action, comprising a vibration measurement subsystem, an axial cable subsystem, a piezoelectric system, and a control system.

[0022] The main truss structure includes, but is not limited to, a slender truss structure composed of repeating units connected end to end, generally as follows: Figure 1 As shown in Figure 1. There are no restrictions on the internal structure of its repeating units, the constituent materials, or the cross-sectional shape along the extension direction; only the slender characteristics of the overall structure need to be satisfied.

[0023] The vibration measurement subsystem, consisting of vibration sensors deployed at a specific point in the system, aims to measure vibration in real time as feedback signals for active vibration suppression. There are no additional requirements regarding the placement of these sensors, nor are there any restrictions on the specific physical quantities measured. Vibration measurement sensors can be selected from, but are not limited to, displacement photogrammetry, laser vibrometers, and accelerometers.

[0024] The axial cable subsystem is arranged along the truss axis and has a real-time control function to adjust the cable tension, used to suppress large-amplitude vibration deformation. It includes one set of cables, one tension actuator, and one tension measurement feedback mechanism. The cable material can be high-modulus materials such as carbon fiber and aramid fiber, without additional restrictions. The tension actuator can directly apply force to the cable, adjusting its tension in an open-loop manner; optional forms include, but are not limited to, linear motors, articulated motors, and voice coil motors. The tension measurement feedback mechanism is used to detect the tension value in the cable in real time and feed this signal back to the control system to achieve closed-loop tension regulation; its type includes, but is not limited to, tension / compression sensors, spring force measuring mechanisms, and piezoelectric strain sensors.

[0025] The piezoelectric system employs piezoelectric actuators, driven by voltage, and features real-time displacement control. Embedded in certain members of a truss, it suppresses high-frequency micro-vibrations; the specific embedding location is unrestricted. It comprises a set of piezoelectric ceramic modules and a matching housing assembly. The piezoelectric ceramic modules are capable of micron-level displacement output, exhibiting short strokes and fast response; there are no restrictions on their ceramic stacking method or number of layers. The housing assembly serves to unload torque and shear forces from the piezoelectric ceramic modules and protect them.

[0026] The control system can collect vibration measurement signals from the vibration measurement subsystem as feedback, calculate based on the control algorithm, and finally output the output signal to the axial cable subsystem and the piezoelectric system to suppress vibration. The choice of control system includes, but is not limited to, a computer host.

[0027] The control method for the wide-amplitude vibration suppression system of truss structures is as follows: First, based on the structural vibration information measured by the vibration measurement subsystem, the current vibration condition is classified. Then, a graded control strategy is adopted to suppress the vibration. A criterion displacement value is set. A When the vibration amplitude is ≤ A When the amplitude is greater than 100, only the piezoelectric system is activated and the axial cable subsystem is shut down to avoid additional vibration problems caused by the control dead zone of the axial cable subsystem; while when the amplitude is greater than 100, the axial cable subsystem is activated. A The axial cable subsystem is activated, and the piezoelectric system is deactivated. The control law is selected as follows:

[0028] in and These are the vibration displacement and velocity obtained after measurement and calculation. and These are the input control quantities for the piezoelectric system and the axial cable subsystem, respectively. and These are the control laws for the piezoelectronic system and the axial cable subsystem, respectively.

[0029] Example: Specific implementation of a wide-amplitude vibration suppression system for truss structures, for example Figure 1 , Figure 2 As shown. Figure 1 The diagram illustrates the overall implementation, wherein the main truss structure 1 is a triangular prism truss structure, 2 is a vibration measurement subsystem, 3 is an axial cable subsystem, and 4 is a piezoelectronic system. Figure 2 This is a detailed schematic diagram of the axial cable subsystem and the piezoelectric system, where 31 is the tension actuator, 32 is the tension measurement feedback mechanism, and 33 is the cable.

[0030] In the axial cable subsystem, the tension actuator 31 uses a servo joint motor, which is directly connected to the control system via a cable and directly controlled by the control system. The tension measurement and feedback mechanism 32 uses a strain gauge sensor, which is directly connected to the control system via a cable and directly collects the tension feedback signal. The cable 33 uses a 2mm diameter double-strand Kevlar rope, balancing strength and elasticity. The cable is arranged along the truss axis and located outside the structural envelope. The servo joint motor outputs control system signals to control the cable tension in real time, achieving dynamic tension adjustment from 0-2000N, which can change the bending stiffness of the truss structure in real time.

[0031] The piezoelectric ceramic module in the piezoelectric system uses a single-layer stacked piezoelectric ceramic actuator (displacement output ±50μm), which is integrated into the root member of the truss in an embedded configuration. The module is equipped with a self-sensing circuit to monitor the actuator status in real time and compensate for hysteresis nonlinearity. It is also equipped with a matching housing assembly, the purpose of which is to unload the torque and shear force of the piezoelectric ceramic and protect the piezoelectric ceramic module.

[0032] In this embodiment, A is 0.1 mm. Based on the real-time measured vibration, the current vibration situation is classified, and then a graded control strategy is adopted to suppress the vibration. The control law is as follows:

[0033] in This is the control parameter matrix in the state-space equations. This represents the solution to the Riccati equation corresponding to the state-space equation. This is the stiffness variation matrix of the structure when the axial cables are tightened and relaxed. and These are the vibration displacement and velocity obtained after measurement and calculation. and These are the input control quantities for the piezoelectronic system and the axial cable subsystem, respectively.

[0034] This invention can suppress vibrations in the combined cases of low-frequency large-amplitude deformation (1-10mm amplitude) and high-frequency small-amplitude vibration (10-100um amplitude), solving the problem that traditional control methods cannot achieve both simultaneously. It can simultaneously cover the entire wide amplitude range of suppression from quasi-static deformation to high-frequency micro-vibration.

[0035] The parts of this invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A wide-amplitude vibration suppression system for truss structures, characterized in that: It includes a vibration measurement subsystem, an axial cable subsystem, a piezoelectric system, and a control system; Vibration measurement subsystem: measures the vibration of the truss structure in real time and feeds it back to the control system; Piezoelectric system: Embedded in the truss structure, it generates real-time displacement based on the piezoelectric control signal from the control system; Axial cable subsystem: includes cables, tension actuators, and tension measurement feedback mechanisms; the cables are arranged along the truss axis, the tension measurement feedback mechanism detects the tension value in the cables in real time and feeds it back to the control system, and the tension actuator applies tension to the cables according to the drive control signal of the control system; Control system: Based on the feedback information from the vibration measurement subsystem, the current vibration status of the truss structure is determined, and the working status of the axial cable subsystem and the piezoelectric system is determined. PID control is adopted. When the piezoelectric system is working, a piezoelectric control signal is generated based on the feedback information from the vibration measurement subsystem and sent to the piezoelectric system. When the axial cable subsystem is working, a drive control signal is generated based on the feedback information from the vibration measurement subsystem and the feedback information from the tension measurement feedback mechanism and sent to the axial cable subsystem.

2. The wide-amplitude vibration suppression system for truss structures according to claim 1, characterized in that: The piezoelectric system is a piezoelectric material actuator. The piezoelectric material actuator includes a set of piezoelectric ceramic modules and a housing assembly. The set of piezoelectric ceramic modules is stacked and placed inside the housing assembly. The size of the housing assembly matches the size of the stacked piezoelectric ceramic modules.

3. The wide-amplitude vibration suppression system for truss structures according to claim 1, characterized in that: Tension actuators include, but are not limited to, linear motors, articulated motors, or voice coil motors.

4. The wide-amplitude vibration suppression system for truss structures according to claim 1, characterized in that: Tension measurement feedback mechanisms include, but are not limited to, tension / compression sensors, spring force measuring mechanisms, and piezoelectric strain sensors.

5. The wide-amplitude vibration suppression system for truss structures according to claim 1, characterized in that: The cable is made of a high-modulus material, and its axial modulus is not less than 30 GPa when tensioned.

6. The wide-amplitude vibration suppression system for truss structures according to claim 1, characterized in that: The control system determines the current vibration status of the truss structure based on feedback information from the vibration measurement subsystem, and determines the operating status of the axial cable subsystem and the piezoelectric system, as follows: Preset displacement criterion values A ; The current vibration amplitude of the truss structure is determined based on the feedback information from the vibration measurement subsystem. If the vibration amplitude is ≤ A At this time, the piezoelectric system is activated and the axial cable subsystem is deactivated; When the vibration amplitude is > A At this time, the axial cable subsystem is activated and the piezoelectric system is deactivated.

7. The wide-amplitude vibration suppression system for truss structures according to claim 1, characterized in that: The control quantity input from the control system to the piezoelectronic system satisfy: in This represents the control parameter matrix in the state-space equations of the truss structure. This is the solution to the Riccati equation corresponding to the state-space equations of the truss structure. and These are the vibration displacement and velocity calculated based on feedback information from the vibration measurement subsystem. It is a state-space vector formed by splicing vibration displacement and velocity.

8. A wide-amplitude vibration suppression system for truss structures according to claim 1, characterized in that: The control quantity input from the control system to the axial cable subsystem satisfy: and These are the vibration displacement and velocity calculated based on feedback information from the vibration measurement subsystem. This is the stiffness variation matrix of the truss structure when the axial cables are tightened and relaxed. It is a symbolic function.

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