Research On Active-passive Integrated Actuator Based On Piezoelectric Ceramic And Multi-dimensions Vibration Isolation System

In the modern aerospace engineering,the requirements of the positional accuracy and observation resolution for the sensitive instruments on the spacecraft.The tiny vibrations will be inevitably caused by the normal working components of the spacecraft,such as the momentum wheel,control moment gyroscopes,solar panels.The tiny vibrations become the primary broblems,which affect the normal work of the sensitive instruments.The sensitive instruments on the spacecraft bear the operation,such as the navigation,measurement,position,observation and aiming.The vibrations will cause the lack of accuracy and reliability,even affect the maneuvering performance,stability of data transmission of the spacecraft.The serious vibration will bring flight failure.For the multiple degree of freedom vibration isolation problems of the sensitive instruments on the spacecraft and aircraft,this thesis proposes the appropriate isolator,the multiple degree of freedom vibration isolation platform,active control strategy and achieve the sensitive instrumengts vibration isolation,combined with the National Natural Science Foundation of China.Base on the advantages and disadvantages of the passive vibration isolation and active vibration isolation,the disadvantages of the existing vibration isolators,a novel hybrid vibration actuator based on the piezoelectric actuator and rubber isolator is presented,which features simple and compact structure,small size,lightweight,thin rod shape.The dynamic model of the hybrid actuator is estalibished and simulated.The hybrid actuator prototype is developed for the experiment.The experimental results demonstrate that the vibrations are significantly reduced by the proposed hybrid actuator.The piezoelectric actuator can eliminate the resonance peak significantly and the rubber isolator can isolate the high frequency vibration and ensure the reliability of the hybrid actuator.The piezoelectric actuator exhibits non-linear hysteresis between the output displacement and driven voltage,which seriously affects its precision,response speed and performance.The static and dynamic experiments are performed to validate the rates-dependent characteristics of our proposed hybrid actuator,including the preload-dependent,frequency-dependent and amplitude-dependent characteristics.The Bouc-Wen model and corresponding parameter identification method is proposed.The experimental system is implemented to evaluate the effectiveness of the proposed model and parameter identification method.The results indicate that the output displacement predicted by proposed Bouc-Wen mathematics model can match the measured data very well.Two linearization methods named the feedforward linearization and feedforward compensation & PI feedback hybrid linearization control are presented,respectively,which are based on the proposed Bouc-Wen model.To evaluate the effectiveness of the proposed linearization controllers,the simulations are implemented.The results demonstrate that both linearization controllers for the hybrid actuator can linearize the hysteresis characteristics and improve control accuracy.In addition,the feedforward compensation & PI feedback hybrid linear controller can achieve higher linearity than feedforward compensation controller.To achieve the six degree of freedom vibration isolation of the sensitive payloads,the orthogonal vibration isolation module is proposed based the proposed hybrid actuator.The disturbances of the spacecraft payload mainly come frome micro vibration,and the output displacement of the piezoelectric actuator is micro level,so the effect of the hinge clearance is amplified.Aming to this condition,a novel type spherical hinge without clearance is proposed and applied on the orthogonal vibration isolation module.Aming to the large mass,lare diameter and small installation space sensitive payloads which ratio of the diameter and installation height is very great,a six-dimension vibration isolation platform composed with three orthogonal vibration isolation modules is presented.The dynamic model of the six-dimension vibration isolation platform is established using Lagrange equation,which makes preparation for dynamic characteristics analysis of the six-dimension vibration isolation platform.Based on the dynamic model of the six-dimension orthogonal vibration isolation platform employing the hybrid actuator,considering the various uncertainties existing in the multi-body system,such as modeling error,simplification,and unstructured uncertainty of external disturbance,The rubust H? controller is designed.The six-dimension orthogonal vibration isolation platform with rubust H? controller can work under various uncertain factors exist.H? controller is too conservative to sove the structural uncertainty of the dynamic model.The parameter perturbation model with damper and stiffness is established.Based on ? theory,the robust controller is designed,which can greatly reduce the conservatism of the H? controller.According to the simulation analyze,the robust controller of six-dimensional orthogonal vibration isolation platform can effectively isolate vibration of 10Hz~+? frequency band,completely eliminate the first-order resonance peak.The vibration isolation effect is better with excitation frequency increasing.To validate the vibration isolation performance of the six-dimension orthogonal vibration isolation platform,the experiments are implemented.The prototype of the six-dimension orthogonal vibration isolation platform is developed.Aming to the performance indicators and requirements of the sensitive payload,the sensitive payload simulator is desigened and developed.Based on the rapid control prototyping technology,the real-time control system is established.The debuggings of the hardware and software are completed.The excitation is the vertical direction signal.The experimental results show that the six-dimension orthogonal vibration isolation platform employing the hybrid actuator can attenuate the vibration effectively within 18Hz~+?.The passive rubber isolator can achieve certain vibration isolation performance,which can improve the stability of the whole system,even if the active control is failed.