Design and analysis of a 3D piezoelectric micro-positioning platform of lever-compound bridge type

JIN Junjie; WANG Shuo; SUN Feng; HAO Yansong; XU Fangchao; ZHANG Xiaoyou

doi:10.7688/j.issn.1000-1646.2025.02.11

Abstract：[Objective]In response to the problems of large volume and small stroke of current micro-positioning platforms,a new displacement amplification mechanism of a lever-compound bridge type was proposed,and a three-degree-of-freedom piezoelectric micro-positioning platform that could achieve large-stroke motion was designed.[Methods]First,the structure of the piezoelectric micro-positioning platform was proposed,and its working principle was analyzed.The piezoelectric actuator generated initial displacement,which was first amplified by the compound bridge structure and then amplified again by the lever mechanism.The final amplified displacement was output to the moving platform.In addition,the lever and compound bridge mechanisms for displacement amplification were designed and optimized,and the stiffness model and displacement amplification ratio mathematical model of the lever and compound bridge mechanisms for displacement amplification were established with theories of statics,material mechanics,and elasticity.According to the theoretical model,the dimensions of the lever and compound bridge mechanisms as displacement amplifiers were optimized,and the overall amplification factor after optimization was 20.6.Then,the structure of the flexible hinge was optimized,and finite element simulation was conducted on four typical notch shapes.After the analysis of the relationship between the output displacement and input force for the four flexible hinges,the flexible hinge of the straight beam type was selected.Finite element simulation was performed on the overall piezoelectric micro-positioning platform to analyze the displacement output performance and rotational output performance around the x-axis and y-axis of the piezoelectric ceramic actuator after deformation amplification.Finally,output testing was conducted on the designed piezoelectric micro-positioning platform.Experimental verification was conducted on the z-axis direction displacement output performance of the displacement amplifier and its rotational output performance around the x-axis and y-axis.[Results]Finite element simulation shows that the maximum output displacement of the piezoelectric micro-positioning platform in the z-axis direction is 740 μm with a simulation magnification factor of 15.The maximum output rotation angles around the x-axis and y-axis are 0.83° and 0.86°,respectively.The output test of the piezoelectric micro-positioning platform shows that the boost curve does not coincide with the buck curve,and there is a hysteresis phenomenon.The maximum output displacement in the z-axis direction is 706 μm.When the voltage is 30 V,the hysteresis displacement is the largest,which is 65 μm.The maximum output angle around the x-axis is 0.8°,and that around the y-axis is 0.79°.When the voltage is 30 V,the maximum hysteresis angle around the x-axis is 0.062°.When the applied voltage is 45 V,the maximum hysteresis angle around the y-axis is 0.047°.Compared with the simulation results,the maximum errors in motion along the z-axis direction and in rotation around the x-and y-axes are 34 μm,0.03°,and0.07°,respectively,with corresponding maximum relative errors of 4.6％,3.6％,and 8.1％.[Conclusion]The piezoelectric micro-positioning platform based on the lever and compound bridge mechanisms for displacement amplification effectively solves the problem of small output displacement of piezoelectric ceramics,achieving large-stroke motion.