Research On Theories And Related Techniques For Motion Decoupling And Control Of Tri-Axial Standard Vibrators

In this dissertation,the theories and techniques related to motion decoupling and control for the tri-axial standard vibrator were studied for the technique problem of outputting an am-plitude-phase controllable and low distortion tri-axial sinusoidal excitation signals synchro-nously.The main topics analyzed contain the design theories of a tri-axial standard vibrator and its motion decoupling structures,the optimal design theories for the vibration transmission of the motion decoupling structures in the tri-axial standard vibrator,and the techniques for the tri-axial vibration waveform distortion control and the amplitude-phase decoupling control.In chapter 1,the significance and content of the dissertation were presented.First,the con-tents and methods of vibration calibration for tri-axial vibration sensors were introduced,and the significance of the tri-axial vibration calibration system based on the tri-axial standard vi-brator was analyzed.Then,the recent research at home and abroad was analyzed on the topics of the multi-axial vibrator used for vibration test,the tri-axial standard vibrator and the related decoupling and control technologies.At last,the technical challenges when developing a tri-axial standard vibrator system and the main research contents of the dissertation were pre-sented,respectively.In chapter 2,the design theories of the tri-axial standard vibrator and its motion decoupling structures were studied.First,the theory and simulation of the space tri-axial vibrations syn-thesis and decomposition were analyzed,and the trajectory synthesis principles of the two-axial and tri-axial vibrations with the same frequency and the decomposition principles of the compound tri-axial spatial vibrations were described,respectively.Then,the overall struc-ture of the tri-axial standard vibrator and its compound motion decoupling structures based on the aerostatic bearing and orthogonal leaf spring were designed,which could output the tri-axial space decoupling vibration signals.Finally,the key technical problems were obtained on the design of the mechanical decoupling structure and motion control system for the tri-axial standard vibrator based on the results of the theoretical and simulation analysis of the residual coupling characteristics for the equivalent tri-axial coupling model.In chapter 3,the optimization design theories were researched for the vibration transmis-sion capability of the motion decoupling structures of the tri-axial standard vibrator.In order to improve the horizontal vibration transmission capability of the tri-axial standard vibrator,the decoupling structure was designed based on the partial porous aerostatic guide rail.Referring to the results of the numerical calculation,simulation through Fluent for the load capacity and stiffness of the gas film and the experimental measuring of the vibration transmission charac-treistics,the porous restrictor geometries and the operating parameters of the aerostatic guide rail decoupling structure were designed optimally.In order to improve the vertical vibration transmission capability of the orthogonal leaf spring decoupling structure,the vibration trans-mission characteristics of the vertical motion component were analyzed based on simulations and experiments when the thickness,length and material of the leaf spring were changed.As a result,the optimal design of the vertical motion decoupling component based on the orthogonal leaf spring was realized.In chapter 4,the vibration waveform distortion control techniques of the tri-axial standard vibrator were studied.First,based on the theoretical analysis of the principle of negative feed-back suppression distortion and the structure of single-axis electromagnetic vibrator and its frequency response characteristics,a vibration velocity signal acquisition technique based on induction coil was proposed and a velocity feedback control system for the horizontal sin-gle-axial vibrator was constructed.The closed-loop transfer function model was identified and the stability of the system was also analyzed.The validity of the proposed feedback control technique was verified by the distortion test of the low-frequency vibration acceleration wave-form of the horizontal vibrator system.Then,for the vertical vibration output of the tri-axial standard vibrator,a second harmonic suppression technique based on the compensation method was proposed.By adding the harmonic compensation signal,which was related to the ampli-tude and phase of the two horizontal vibration signals,to the input signal of the vertical vibrator system,the second harmonic coupling component for the vertical vibration was effectively suppressed.In chapter 5,the techniques of tri-axial vibration amplitude and phase decoupling control for the tri-axial standard vibrator were studied.First,a motion decoupling control technique based on neural network inverse model was proposed for the tri-axial standard vibrator.Based on the analysis of the system reversibility,the neural network inverse model of the tri-axial standard vibrator system was identified.The inverse model was connected before the original system to obtain three independent decoupling subsystems along the x,y and z axes.Then,the motion decoupling was realized.The experimental test results of the orthogonal vibration sup-pression ratio when the tri-axial standard vibrator was excited along single-axis and two axes verified the effectiveness of the proposed motion decoupling control technique.Then,a kind of vibration amplitude-phase decoupling control technique based on iterative method was pro-posed.By measuring the amplitude and phase of the tri-axial vibration acceleration signals,the amplitude and phase of each single-axis vibration signal were corrected to realize the accurate decoupling control of the amplitudes and phases of the tri-axial vibrations output from the tri-axial standard vibrator.The effectiveness of the proposed iterative control technique was verified by the experimental tests of the control accuracy for the tri-axial vibration amplitudes and phases.In chapter 6,the experimental tests for the developed tri-axial standard vibrator system were studied.Based on the research results of the theories and related techniques for motion decoupling and control,a tri-axial standard vibrator system was developed which could syn-chronously output tri-axial,low distortion and amplitude-phase controllable sinusoidal excita-tion signals.The system consisted of the mechanical excitation device and the measurement and control component.The validity and correctness of each theory and simulation analysis were verified by the experimental tests of the amplitudes,phases and distortions of the single-axis and tri-axial vibration excitation signals.In chapter 7,the achivements of this dissertation were summarized,and the future research for further study was prospected.