| MEMS(Micro-Electro-Mechanical System)inertial sensor has the advantages of small size and lightweight.It has a wide application in the fields of aerospace,national defense and security.However,after long-term storage and long-distance transportation,MEMS inertial sensor presents the reliability problems of bias and scale factor drift,which greatly limits its application in the high-precision measurement field.In order to ensure the measurement reliability of MEMS inertial sensor,the device is recalibrated prior to use for accurate measurements.Therefore,the design of an inertial reference platform has become an inevitable demand for device recalibration.Calibration equipment such as centrifuges are complicated to install and bulky,so they are not suitable for in-site real-time calibration.Therefore,it is necessary to design a calibration platform that can provide acceleration and angular velocity reference signals,and is easy to install and move to realize the in-site real-time calibration of MEMS inertial sensor.The dissertation takes the piezoelectric vibratory stage with translation and rotation capabilities as the research object.It realizes the inertial reference signal output of the three degree of freedom vibration of the platform through structural design,driving method design,vibration error analysis,fabrication and experiment,which lays a solid theoretical and hardware foundation for the promotion of the in-site real-time calibration platform of MEMS inertial sensor in the future.The main contents are as follows:1.Complete the structural design of MEMS piezoelectric vibratory stage.The MEMS piezoelectric vibratory stage is composed of a square central platform and four L-shaped piezoelectric folded beams.The stiffness of L-shaped piezoelectric folded beam and the stiffness of translation and rotation of MEMS piezoelectric vibratory stage are derived.The multi-electrode driving method of L-shaped piezoelectric folded beam is studied.The electromechanical model of piezoelectric folded beam in matrix form is established.The relationship between multi-parts and the piezoelectric folded beam is described by matrix operation.Based on this,the multi-electrode driving method of L-shaped piezoelectric folded beam is analyzed,the multi-electrode driving method of MEMS piezoelectric vibratory stage is studied,and the optimal driving scheme of MEMS piezoelectric vibratory stage is given.2.The causes of off-axis error of MEMS piezoelectric vibratory stage are analyzed.It is pointed out that the stiffness mismatch of four L-shaped piezoelectric folded beams supporting MEMS piezoelectric vibratory stage is one of the main causes of off-axis error of the vibratory stage.According to the electromechanical coupling model of L-shaped piezoelectric folded beam,the correlation between the structural parameters of piezoelectric folding beam and the off-axis error of vibratory stage is studied.The method of improving the structural parameters of L-shaped piezoelectric folded beam to reduce the off-axis error of the vibratory stage is proposed.The results show that the relative off-axis error of the vibratory stage reduced from 5.9% to 0.6%.3.The influence of residual stress on the translational performance of MEMS piezoelectric vibratory stage is studied.According to the simplified model of residual stress,the relationship between residual stress and deformation of piezoelectric folded beam is studied,and finally the influence of deformation of piezoelectric folded beam on the performance of vibratory stage is analyzed.The influence of residual stress on the performance of MEMS piezoelectric vibratory stage is analyzed.It is concluded that the stress gradient of residual stress in the thickness direction of piezoelectric folded beam is the reason for the warping of piezoelectric beam and the initial displacement of the vibratory stage.And the translational vibration waveform of MEMS piezoelectric vibratory stage with initial displacement is distorted.4.The influence of hysteresis error on the performance of MEMS piezoelectric vibratory stage is analyzed.According to the characteristics of piezoelectric vibratory stage,the hysteresis compensation method combining feedforward and feedback is adopted.This method establishes a hysteresis model based on polynomial fitting according to the experimental data,and builds a feedforward controller through this model.The method of hysteresis compensation has the risk of over compensation.In view of this,the function of limiting over compensation is added to the feedforward controller to improve the reliability of the feedforward controller.This dissertation combined with theoretical analysis and experimental verification,the structure design,driving method research and error analysis of MEMS piezoelectric vibratory stage are completed,and the three degree of freedom vibration of MEMS piezoelectric vibration table is realized.The main contribution is to establish a piezoelectric folded beam matrix electromechanical model and give the optimal driving scheme of the piezoelectric vibratory stage.A method of improving the structural parameters of L-shaped piezoelectric folded beam to reduce the off-axis error of vibratory stage is proposed.In addition,the influence of piezoelectric hysteresis effect and residual stress on the performance of MEMS piezoelectric vibratory stage is analyzed.It lays a solid foundation for the in-site real-time calibration of MEMS inertial sensors in the future. |
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