Research On Dispensing Applications Based On Piezoelectric Actuator

With the improvement of science and technology,dispensing technology whose core driving element is piezoelectric,has been rapidly developed.As an actuator,piezoelectric has the characteristics of high positioning accuracy,big stiffness,and fast response,what's more,it can also be used as sensors in other areas.In the application of dispensing technology,the output force of piezoelectric has a big influence on dispensing accuracy.The traditional method adjusts the output force of piezoelectric through experimental tests,which often wastes time and increases a lot work to testers.In addition,the output displacement of the piezoelectric actuator is about tens of microns,which can't meet the requirement of the dispensing's stroke.To solve these problems,this thesis studies the self-sensing characteristics of stacked piezoelectric and designs a new type displacement amplification mechanism with flexural hinges,which can be used for dispensing.In order to study the self-sensing characteristics of piezoelectric,the output characteristics and boundary conditions have been analyzed.And the self-sensing models based on bridge circuit and state observer are brought out.Comparing the two models,it can be known that the equilibrium condition of bridge circuit is difficult to be realized,and it is often used for the self-sensing of piezoelectric element.And state observer method is achieved by collecting the charge of piezoelectric surface,which can be converted into force and displacement information easily.Based on these theories,the drive voltage signal and acquisition codes are programed by Matlab and Lab VIEW,and the feasibility for piezoelectric self-sensing is verified.The research of displacement amplification mechanism mainly discusses the existing amplification mechanism models,and selects a kind of mechanism with right-circle flexural hinges which is suitable for the dispensing technology.Compared with right-angle hinges,right-circle hinges have higher life and accuracy.What's more,a new amplification ratio formula is proposed,and the influence of hinges' parameters have been simulated by ANSYS.After completing the coupling of piezoelectric and amplifier,the output performance of whole mechanism is tested and the applicability and consistency of this mechanism in dispensing application is also verified by dispensing test platform.