Method and apparatus for frequency multiplication rejection in micro-vibration simulator

Abstract

The application is suitable for the field of ground simulation technology of space micro-vibration source, and provides a frequency multiplication suppression method and device of a micro-vibration simulator; the frequency multiplication suppression method is based on the corresponding device, and the transfer function of a specific frequency sine excitation force and the corresponding measured platform vibration acceleration is calculated. Similarly, the transfer function of the frequency of the frequency multiplication response in the simulation process is calculated, so that the size of the sine excitation force corresponding to the frequency multiplication can be inversely deduced according to the transfer function and the acceleration; finally, the opposite sine excitation force at the frequency multiplication is input in the simulation process, which can offset the sine excitation force leading to the frequency multiplication response, thereby suppressing the frequency multiplication response in the micro-vibration simulation process and improving the accuracy of the vibration simulation.

Description

Technical Field

[0001] This application belongs to the field of ground simulation technology for space micro-vibration sources, and particularly relates to a method and device for frequency suppression of micro-vibration simulators. Background Technology

[0002] Currently, to overcome the limitations imposed by the space micro-vibration environment on the imaging quality of high-precision remote sensors, it is necessary to design and manufacture micro-vibration simulators capable of simulating multi-dimensional space micro-vibration environments. The Gough-Steward platform, capable of generating six degrees of freedom motion, is commonly used as a micro-vibration simulator. However, issues such as the nonlinear stiffness of the spring plates within its six legs and structural gaps in the hinges connecting the legs to the upper and lower platforms cause harmonic distortion during micro-vibration simulations. That is, during the simulation, harmonic responses with accelerations of approximately or even greater magnitude occur at harmonics of the preset frequency. Harmonic distortion interferes with the accuracy of the simulation. Although the harmonic distortion can be improved by modifying the spring plate and hinge structure, it is difficult to completely eliminate. Existing technologies have shortcomings. Summary of the Invention

[0003] The purpose of this application is to provide a method and device for suppressing frequency overtones in a micro-vibration simulator, which aims to solve the problem of frequency overtones occurring during multi-frequency line spectrum micro-vibration simulations due to structural design issues in six-degree-of-freedom micro-vibration simulators.

[0004] On the one hand, this application provides a method for frequency harmonic suppression in a micro-vibration simulator, the method comprising the following steps:

[0005] s1. Input a sinusoidal excitation force of a preset frequency to each leg of the micro-vibration simulator, and measure the acceleration generated at the center point of the upper platform of the micro-vibration simulator in the three-dimensional axial direction and the three-dimensional circumaxial direction to form the six-dimensional acceleration corresponding to each leg;

[0006] s2. Based on the six-dimensional acceleration corresponding to each leg of the micro-vibration simulator and the sinusoidal excitation force at a preset frequency, construct the transfer function at the preset frequency;

[0007] s3. Based on the transfer function and the six-dimensional acceleration of the target to be simulated, calculate the sinusoidal excitation force at the target frequency in reverse;

[0008] s4. Apply the sinusoidal excitation force at the target frequency to each outrigger and measure the corresponding acceleration generated at the center point of the upper platform of the micro-vibration simulator; if an overtone response is generated at an overtone of the target frequency, record the response amplitude and phase at that overtone, return to steps s1 to s2, and measure the transfer function at the overtone using the overtone frequency as the preset frequency;

[0009] s5. Calculate the sinusoidal excitation force at the octave frequency by using the acceleration of the response at the octave frequency and the transfer function at the octave frequency; use the reaction force of the sinusoidal excitation force at the octave frequency as a counteracting force, add it to the sinusoidal excitation force at the target frequency, and realize the control of the target frequency and the suppression of the octave frequency response.

[0010] On the other hand, this application also provides a frequency suppression device for a micro vibration simulator that applies any of the methods described above, the device comprising: a micro vibration simulator, a Beckhoff control system, a signal acquisition system, and a terminal PC;

[0011] The terminal PC is electrically connected to the Beckhoff control system, runs a GUI to interact with the operator and sends target commands to control the Beckhoff control system to operate.

[0012] The Beckhoff control system is electrically connected to the micro-vibration simulator, and outputs a driving current of excitation force at a preset frequency to the micro-vibration simulator, and calculates the transfer function and the six-dimensional acceleration of the micro-vibration simulator based on feedback.

[0013] The micro-vibration simulator simulates vibration at a preset frequency based on the driving current;

[0014] The signal acquisition system is electrically connected to the terminal PC. The acceleration sensor of the signal acquisition system is set at the center of the upper platform of the micro-vibration simulator to collect the acceleration of the upper platform of the micro-vibration simulator when it vibrates and feed it back to the terminal PC.

[0015] The signal acquisition system is electrically connected to the Beckhoff system and is used to transmit the acquired acceleration back to the Beckhoff system for transfer function calculation, thereby realizing the control of the micro-vibration simulator.

[0016] This application's octave suppression method is based on a corresponding device, which calculates the transfer function of a sinusoidal excitation force at a specific frequency and the corresponding measured acceleration of the platform vibration. Similarly, the transfer function is also calculated for the frequency at which the octave response occurs during the simulation, allowing the magnitude of the sinusoidal excitation force corresponding to the octave to be deduced from the transfer function and acceleration. Finally, inputting an opposite sinusoidal excitation force at that octave during the simulation cancels out the sinusoidal excitation force causing the octave response, thereby suppressing the octave response in the micro-vibration simulation and improving the accuracy of the vibration simulation. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the implementation of the frequency suppression method for the micro-vibration simulator provided in Embodiment 1 of this application;

[0018] Figure 2 This is a connection diagram of the frequency suppression device of the micro-vibration simulator provided in Embodiment 2 of this application;

[0019] Figure 3 This is a structural block diagram of the identity recognition device for wearable devices provided in Embodiment 3 of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] The specific implementation of this application will be described in detail below with reference to specific embodiments:

[0022] Example 1:

[0023] Figure 1 The implementation flow of the frequency suppression method for the micro-vibration simulator provided in Embodiment 1 of this application is illustrated. For ease of explanation, only the parts related to the embodiments of this application are shown, and are described in detail below:

[0024] A method for frequency octave suppression in a micro-vibration simulator includes the following steps:

[0025] s1. Input a sinusoidal excitation force of a preset frequency to each leg of the micro-vibration simulator, and measure the acceleration generated at the center point of the upper platform of the micro-vibration simulator in the three-dimensional axial direction and the three-dimensional circumaxial direction to form the six-dimensional acceleration corresponding to each leg;

[0026] s2. Based on the six-dimensional acceleration corresponding to each leg of the micro-vibration simulator and the sinusoidal excitation force at the preset frequency, construct the transfer function at the preset frequency;

[0027] s3. Based on the transfer function and the six-dimensional acceleration of the target to be simulated, calculate the sinusoidal excitation force at the target frequency in reverse.

[0028] s4. Apply the sinusoidal excitation force at the target frequency to each outrigger and measure the corresponding acceleration generated at the center point of the upper platform of the micro-vibration simulator; if an overtone response is generated at an overtone of the target frequency, record the response amplitude and phase at that overtone, return to steps s1 to s2, and measure the transfer function at the overtone using the overtone frequency as the preset frequency.

[0029] s5. Calculate the sinusoidal excitation force at the octave frequency by using the acceleration of the response at the octave frequency and the transfer function at the octave frequency; use the reaction force of the sinusoidal excitation force at the octave frequency as a counteracting force, add it to the sinusoidal excitation force at the target frequency, and realize the control of the target frequency and the suppression of the octave frequency response.

[0030] In this application, the sinusoidal excitation force is a driving force whose magnitude varies according to a sinusoidal wave of a preset frequency. For example, the driving force of an AC motor.

[0031] This application measures the corresponding six-dimensional acceleration by inputting a sinusoidal excitation force (the value and number of the preset spectrum can be determined according to requirements) at a preset frequency. Then, based on the six-dimensional acceleration and the input sinusoidal excitation force, a transfer function of the two at the preset frequency is constructed.

[0032] When the six-dimensional acceleration to be simulated is determined (the target frequency corresponding to the six-dimensional acceleration is determined, that is, one of the preset frequencies mentioned above, and its corresponding transfer function can be determined), the driving force, that is, the sinusoidal excitation force at the target frequency, can be determined by back-calculating the target six-dimensional acceleration corresponding to the target frequency based on the transfer function.

[0033] Similarly, when a harmonic response is generated, its frequency is one or more multiples of the target frequency. Simultaneously, its corresponding six-dimensional acceleration can be measured. This allows for the derivation of the corresponding excitation force at the harmonic. Inputting its reaction force can cancel the excitation at that harmonic, suppressing the harmonic response at that harmonic. When there are multiple harmonic responses, processing them one by one yields multiple harmonic cancelling forces.

[0034] By inputting the canceling forces of each harmonic frequency together with the sinusoidal excitation force at the target frequency into the micro-vibration simulator, the simulated vibration will not exhibit harmonic response.

[0035] In practical implementation, this application uses complex numbers to describe the sinusoidal vibration amplitude, frequency, and phase relationship of the sinusoidal excitation force; for example, the amplitude is f, the preset frequency is ω, and the phase is... The sinusoidal vibration can be adopted It means that among them in This represents the imaginary part of the complex number. The following steps are used to perform specific data calculations.

[0036] Step 1: Input the following sinusoidal excitation force F = [fe] to each of the 6 legs of the micro-vibration simulator. jω ,0,0,0,0,0,0],Of the six legs, only the first leg has a sinusoidal vibration force with an amplitude of f and a preset frequency of ω, while the other five legs do not apply any active force.

[0037] Step 2: Following Step 1, the upper platform of the micro-vibration simulation platform will vibrate. The complex expression of the six-dimensional acceleration generated at the center point of the upper platform at this time is: Where a 11 a represents the magnitude of the translational acceleration in the x-direction at the center point of the upper platform. 21 a represents the magnitude of the translational acceleration in the y-direction at the center point of the upper platform.31 a represents the magnitude of the translational acceleration in the z-direction at the center point of the upper platform. 41 a represents the magnitude of the rotational acceleration of the center point of the upper platform about the x-axis. 51 a represents the magnitude of the rotational acceleration of the center point of the upper platform about the y-axis. 61 This represents the magnitude of the rotational acceleration of the center point of the upper platform about the z-axis. The phase difference between the translational acceleration in the x-direction at the center point of the upper platform and the sinusoidal excitation force in step 1. The phase difference between the y-axis translational acceleration at the center point of the upper platform and the sinusoidal excitation force in step 1. The phase difference between the z-axis translational acceleration at the center point of the upper platform and the sinusoidal excitation force in step 1. The phase difference between the rotational acceleration of the upper platform's center point about the x-axis and the sinusoidal excitation force in step 1. The phase difference between the rotational acceleration of the center point of the upper platform about the y-axis and the sinusoidal excitation force in step 1. The phase difference between the rotational acceleration of the center point of the upper platform around the z-axis and the sinusoidal excitation force in step 1.

[0038] Step 3, similar to steps 1 and 2, involves applying F = [0, fe] respectively. jω ,0,0,0,0],F=[0,0,fe jω [0,0,0,0],F=[0,0,0,fe jω [0,0,0],F=[0,0,0,0,fe jω ,0],F=[0,0,0,0,0,fe jω The six-dimensional acceleration of the center point of the upper platform under the corresponding outrigger excitation force was measured and denoted as A2, A3, A4, A5, and A6.

[0039] Step 4: The transfer function matrix of the six-dimensional acceleration at the center point of the upper platform relative to the excitation force of the six outriggers can be calculated using the following formula:

[0040]

[0041] Step 5: After setting the target acceleration, calculate the magnitude of the input target excitation force based on the transfer function at different frequencies and the required target acceleration. The formula is: F(ω)=H(ω) -1 A(ω); where H(ω) -1 The inverse matrix of H(ω) above represents the target acceleration. a 1～6 α 1～6 The magnitude and phase of the six-dimensional acceleration at the center point of the upper platform are represented by the two values, respectively. The force F(ω) obtained by solving is in the form of a 6*1 matrix. Among them, f1～6 θ 1～6 These represent the amplitude and phase of the target excitation force (the corresponding sinusoidal excitation force calculated from the target acceleration using the transfer function) that should be input to the six outriggers, respectively.

[0042] Step 6: After inputting the sinusoidal excitation force obtained in the previous step to the six legs of the simulator, when the target acceleration appears at the center of the upper platform of the micro-vibration simulator at frequency ω, accelerations of approximately or even greater magnitude may occur at 2ω, 3ω, ..., nω, i.e., the harmonic phenomenon. At this time, the set of accelerations at the center point of the upper platform (including all accelerations at the original frequency and its harmonics) is: A(ω) + A1(2ω) + A2(3ω) + ... + A n-1 (nω); where the subscript of A indicates the acceleration sequence number at different harmonic frequencies.

[0043] Step 7: To suppress these accelerations occurring at the harmonics of the preset frequency, this application further calculates the transfer function corresponding to the harmonic acceleration through steps s1 to s3 above and inversely derives its corresponding sinusoidal excitation force. Based on the formula: F new (ω)=H(ω) -1 A(ω)-H(2ω) -1 A1(2ω)-H(3ω) -1 A2(3ω)-…-H(nω) -1 A n-1 (nω) cancels out the acceleration at the harmonic frequency. That is, while inputting the sinusoidal excitation force of the preset frequency, an opposite canceling force of the sinusoidal excitation force at the frequency corresponding to the harmonic phenomenon is also input, thereby suppressing the occurrence of the harmonic phenomenon.

[0044] Furthermore, the preset frequency range in step s1 is 5Hz to 300Hz; the micro-vibration simulator is equipped with six legs.

[0045] Furthermore, the six-dimensional acceleration in step s1 includes the translational acceleration amplitude of the upper platform center point in the x direction, the translational acceleration amplitude of the upper platform center point in the y direction, the translational acceleration amplitude of the upper platform center point in the z direction, the rotational acceleration amplitude of the upper platform center point about the x-axis, the rotational acceleration amplitude of the upper platform center point about the y-axis, and the rotational acceleration amplitude of the upper platform center point about the z-axis.

[0046] Furthermore, in step s2, the transfer function is the set of transfer functions corresponding to the excitation forces of the six legs at the same preset frequency.

[0047] Furthermore, in step s1, the sinusoidal excitation force is input to the micro-vibration simulator in the form of a driving current; if a harmonic response is generated in step s1, then the acceleration generated at the center point of the micro-vibration simulator is a composite vibration of multiple frequencies.

[0048] The frequency suppression method for the micro-vibration simulator in this application does not require the construction of a dynamic model. It only requires the extraction of the transfer function based on the actual assembled simulator, and does not depend on the theoretical model, thus possessing excellent control accuracy.

[0049] Example 2:

[0050] Figure 2 , 3 The diagram shows a schematic diagram and a block diagram of the frequency suppression device of the micro-vibration simulator provided in Embodiment 2 of this application. For ease of explanation, only the parts related to the embodiments of this application are shown.

[0051] A frequency suppression device for a micro vibration simulator using any of the above methods, the device comprising: a micro vibration simulator, a Beckhoff control system, a signal acquisition system, and a terminal PC;

[0052] The terminal PC is electrically connected to the Beckhoff control system, runs a GUI to interact with the operator, and sends target commands to control the Beckhoff control system to perform operations.

[0053] Beckhoff's control system is electrically connected to the micro-vibration simulator, outputting a driving current of excitation force at a preset frequency to the micro-vibration simulator, and calculating the transfer function and the six-dimensional acceleration of the micro-vibration simulator based on feedback.

[0054] The micro-vibration simulator simulates vibration at a preset frequency based on the driving current;

[0055] The signal acquisition system is electrically connected to the terminal PC. The acceleration sensor of the signal acquisition system is set at the center of the upper platform of the micro vibration simulator to collect the acceleration of the upper platform of the micro vibration simulator during vibration and feed it back to the terminal PC.

[0056] The signal acquisition system is electrically connected to the Beckhoff system to transmit the acquired acceleration back to the Beckhoff system for transfer function calculation, thereby enabling control of the micro-vibration simulator.

[0057] Furthermore, the micro-vibration simulator is equipped with six legs, which are connected between the upper platform and the lower platform respectively.

[0058] Furthermore, the target instructions include the preset frequency input to the Beckhoff control system and the magnitude of the sinusoidal excitation force corresponding to the preset frequency.

[0059] Furthermore, the calculation of the transfer function and control algorithm of the Beckhoff control system is based on: the excitation force at the preset frequency, the acceleration corresponding to the vibration driven by the excitation force, and the transmission function between the two.

[0060] Furthermore, the six-dimensional acceleration is the set of accelerations corresponding to the six outriggers at the same preset frequency; the transfer function is the set of transfer functions corresponding to the excitation forces of the six outriggers at the same preset frequency.

[0061] This application discloses a frequency harmonic suppression method based on the transfer function of a micro-vibration simulator, utilizing a frequency harmonic suppression device composed of four subsystems: a micro-vibration simulator, a Beckhoff control system, a signal acquisition system, and a terminal PC. First, the transfer function at the desired preset frequency is measured. Based on the transfer function and the target acceleration, the magnitude of the input excitation force is calculated. When an excitation force is input, a frequency harmonic phenomenon occurs at certain frequencies. The excitation force causing this phenomenon is then deduced from the transfer function of the harmonic and the acceleration. Inputting an excitation force opposite to the harmonic frequency can cancel out the acceleration at that harmonic frequency.

[0062] The frequency octave suppression method and apparatus proposed in this application have the following advantages:

[0063] (1) Control theory is simple and does not require complicated formula derivation;

[0064] (2) A closed-loop control system is formed with high control precision, which can accurately simulate multi-degree-of-freedom spatial micro-vibrations;

[0065] (3) No dynamic model needs to be built. The transfer function can be extracted based on the actual simulator, and there is no dependence on the theoretical model.

[0066] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of frequency multiplication rejection for a microvibranium simulator, characterized by, The method includes the following steps: s1. Input a sinusoidal excitation force of a preset frequency to each leg of the micro-vibration simulator, and measure the acceleration generated at the center point of the upper platform of the micro-vibration simulator in the three-dimensional axial direction and the three-dimensional circumaxial direction to form the six-dimensional acceleration corresponding to each leg; s2. Based on the six-dimensional acceleration corresponding to each leg of the micro-vibration simulator and the sinusoidal excitation force at a preset frequency, construct the transfer function at the preset frequency; s3. Based on the transfer function and the six-dimensional acceleration of the target to be simulated, calculate the sinusoidal excitation force at the target frequency in reverse; s4. Apply the sinusoidal excitation force at the target frequency to each outrigger and measure the corresponding acceleration generated at the center point of the upper platform of the micro-vibration simulator; if an overtone response is generated at an overtone of the target frequency, record the response amplitude and phase at that overtone. Returning to steps s1 to s2, using the harmonic frequency as the preset frequency, the transfer function at the harmonic frequency is measured; s5. Calculate the sinusoidal excitation force at the octave frequency by using the acceleration of the response at the octave frequency and the transfer function at the octave frequency; use the reaction force of the sinusoidal excitation force at the octave frequency as a counteracting force, add it to the sinusoidal excitation force at the target frequency, and realize the control of the target frequency and the suppression of the octave frequency response; The sinusoidal excitation force is an AC motor driving force whose magnitude varies according to the sinusoidal wave of a preset frequency.

2. The method of claim 1, wherein, The preset frequency range mentioned in step s1 is 5Hz to 300Hz; the micro-vibration simulator is equipped with six legs.

3. The method of claim 2, wherein, The six-dimensional acceleration mentioned in step s1 includes the translational acceleration amplitude of the upper platform center point in the x direction, the translational acceleration amplitude of the upper platform center point in the y direction, the translational acceleration amplitude of the upper platform center point in the z direction, the rotational acceleration amplitude of the upper platform center point about the x-axis, the rotational acceleration amplitude of the upper platform center point about the y-axis, and the rotational acceleration amplitude of the upper platform center point about the z-axis.

4. The method of claim 1, wherein, The transfer function mentioned in step s2 is a set of transfer functions corresponding to the excitation forces of the six legs at the same preset frequency.

5. The method as described in claim 1, characterized in that, In step s1, the sinusoidal excitation force is input to the micro-vibration simulator in the form of a driving current; if a harmonic response is generated in step s1, the acceleration generated at the center point of the micro-vibration simulator is a composite vibration of multiple frequencies.

6. A frequency doubling suppression device for a micro-vibration simulator using the method of any one of claims 1 to 5, characterized in that, The device includes: a micro-vibration simulator, a Beckhoff control system, a signal acquisition system, and a terminal PC; The terminal PC is electrically connected to the Beckhoff control system, runs a GUI to interact with the operator and sends target commands to control the Beckhoff control system to operate. The Beckhoff control system is electrically connected to the micro-vibration simulator, and outputs a driving current of excitation force at a preset frequency to the micro-vibration simulator, and calculates the transfer function and the six-dimensional acceleration of the micro-vibration simulator based on feedback. The micro-vibration simulator simulates vibration at a preset frequency based on the driving current; The signal acquisition system is electrically connected to the terminal PC and the Beckhoff control system respectively. The acceleration sensor of the signal acquisition system is set at the center of the upper platform of the micro-vibration simulator to collect the acceleration of the upper platform of the micro-vibration simulator during vibration and feed it back to the terminal PC. The signal acquisition system is electrically connected to the Beckhoff control system and is used to transmit the acquired acceleration back to the Beckhoff system for transfer function calculation, thereby realizing the control of the micro-vibration simulator.

7. The apparatus as claimed in claim 6, characterized in that, The micro-vibration simulator is equipped with six legs, which are respectively connected between the upper platform and the lower platform.

8. The apparatus as claimed in claim 7, characterized in that, The target instruction includes inputting a preset frequency of the Beckhoff control system and the magnitude of the sinusoidal excitation force corresponding to the preset frequency.

9. The apparatus as claimed in claim 8, characterized in that, The calculation of the transfer function and control algorithm of the Beckhoff control system is based on: the excitation force at a preset frequency, the acceleration corresponding to the vibration driven by the excitation force, and the transmission function between the two.

10. The apparatus as claimed in claim 9, characterized in that, The six-dimensional acceleration is the set of accelerations corresponding to the six outriggers at the same preset frequency; the transfer function is the set of transfer functions corresponding to the excitation forces of the six outriggers at the same preset frequency.

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