Design And Experimental Study Of A Multi-mode Frictional Inertial Piezoelectric Actuator

With the advantages of high output accuracy,fast response,high output force and easy structural miniaturization,piezoelectric actuators have important applications in the fields as aerospace,integrated circuits,biological cell engineering,optical engineering,micro/nano technology and precision/ultra-precision machining.Frictional inertia piezoelectric actuators have the advantages of simple mechanical structure,high resolution,easy control,large working stroke,etc.But there are also some non-negligible shortcomings:the impact displacement of the inertial impact piezoelectric actuators reduces their load capacity and motion stability,and the backward motion of the inertial stick-slip piezoelectric actuators affects the output speed and positioning accuracy.In practice,the two type actuators can only work in their own field.And their working mode and displacement curve are single due to their unique driving principle and mechanical structure.and are even more limited by their own driving principle and mechanical structure,with a single form of their working mode and displacement output curve.Thisese reduces the environmental suitability of the frrictional inertia piezoelectric actuators,and and limits their output performance and application fields.In view of the above problems,this paper proposes a multi-mode frictional inertia piezoelectric actuator based on compound drive.Three driving modes of the actuator-inertial stick-slip mode,inertial impact mode and compound drive mode-are obtained,which improves its environmental suitability.The compound driving mode compounding the output of the inertial stick-slip and the inertial impact,which can improve the output performance.Accordingly,the main works of this paper are:Firstly,the mechanical structure of the multi-mode actuator is designed and the working principles of the three driving modes are analyzed in detail.Simultaneously,the matrix-based compliance modeling（MCM）method and response surface methodology（RSM）are applied to the theoretical calculation and analysis of the lever-shaped flexibility mechanism（LSFM）and butterfly-shaped flexibility mechanism（BSFM）of the integrated flexibility mechanism（IFM）,which enable the analysis and optimization of structural parameters.The accuracy of the theoretical calculations is verified by comparing the theoretical calculations with the experimental output amplification ratio.Finally,statics and modal analysis are carried out to verify the rationality and safety of the IFM.Then,a prototype of the multi-mode actuator is assembled and an experimental system is established to test the output performance.The test conditions are determined after the experiments as follows:the inertial mass is 750 g and the initial preload displacement is 50μm.The results of the output performance tests show that the displacement of the compound drive mode is equal to the composite of the displacements of the inertial impact mode and the inertial stick-slip mode.The inertial impact mode reaches a maximum speed of 5056.45μm/s at 250 Hz,the inertial stick-slip mode reaches a maximum speed of 10805.70μm/s at450 Hz and the compound drive mode reaches a maximum speed of 10036.72μm/s at 250Hz.The multi-mode actuator has a maximum horizontal load of 220 g and can carry a wide range of vertical loads.The maximum resolution is 93 nm in the inertial impact mode,47nm in the inertial stick-slip mode,and 63 nm in the compound drive mode,separately.The inertial impact mode has a lowest stability,and the stability of the compound drive mode and the inertial stick-slip mode is closed.The compound drive mode compounds the inertial impact with inertial stick-slip,and greatly improves the output performance of the actuator.In addition,the principle analysis and experimental study for the linear smooth motion in the compound drive mode with two signal inputs is carried out.The experimental results show that the goodness-of-fit R~2 in forward and reverse linear smoothing motion with no load is 0.99997 and 0.99987,while R~2 in forward and reverse linear smoothing motion with1 N load is 0.99981 and 0.99970.It proves that compensating backward displacement with impact displacement is an effective method for achieving linear smooth motion.Finally,based on the above research,a typical application example of the multi-mode actuator is presented--scratch testing.A multi-mode actuator is controlled by a control program written using Lab View to complete the scratching process.Then the residual scratch profile is observed.Experimental results show that clear and effective scratches can be produced in all three drive modes.The scratch quality,in descending order,is the compound drive mode with two signal inputs,the inertial stick-slip mode,the compound drive mode with one signal input and the inertial impact mode,demonstrating the application potential of the multi-mode actuator.The multi-mode actuator proposed in this paper increases the environmental suitability of the actuator and the output performance is significantly improved.Particularly,the linear smooth motion can be achieved in the compound drive mode with two signal inputs.The research work is an important guide in improving the output performance of the piezoelectric actuator and expanding the application areas of the piezoelectric actuator.