Research On Linear Piezoelectric Inertial Actuator Based On Asymmetric Stiffness

The asymmetric piezoelectric inertial actuators utilize an asymmetric clamping structure to generate asymmetric stiffness to achieve directional movement of the actuator.In order to make the asymmetric piezoelectric actuators work stably under resonance and improve the output performance of the actuators,it is first proposed to use asymmetric materials clamping to achieve asymmetric stiffness,and then construct a linear piezoelectric inertial actuator based on asymmetric materials clamping.Theoretical modeling,COMSOL simulation analysis and experimental testing of piezoelectric vibrator under asymmetric materials clamping prove the feasibility of using asymmetric materials clamping to generate an asymmetric inertial impact force.Based on this principle,an asymmetric materials clamping linear piezoelectric inertial actuator was designed and manufactured,and the prototype was tested.The results show that the actuator can achieve the goal of stable operation in the resonance state,and has good driving ability,but there are also problems that the friction force cannot be adjusted,and the backlash phenomenon and the resolution is not accurate enough.In order to achieve adjustable friction and reduce backlash,a combination of magnetorheological fluid friction control and piezoelectric inertial actuator was proposed,which uses fixed both ends to improve resolution.A linear piezoelectric inertial actuator with asymmetric clamping at both ends was designed and manufactured,and it was researched and analyzed through theoretical modeling,simulation analysis and experimental testing.The experimental results show that the actuator can continuously adjust the friction by changing the magnetic field strength,so as to control the backlash phenomenon of the actuator prototype.The main research contents of this thesis are as follows:1.Research on Piezoelectric Vibrator with Asymmetric Materials clampingFirst,the driving principle of the piezoelectric vibrator clamped by asymmetric materials were analyzed.The piezoelectric vibrator was researched through theoretical modeling and COMSOL simulation.The results of simulation and theoretical calculations show that under the asymmetric materials clamping,the amplitude of the tip displacement of the piezoelectric vibrator vibrates up and down is obviously different,which shows that the use of asymmetric materials clamping causes the piezoelectric vibrator to produce an asymmetric inertial impact force is feasible.Secondly,the relationship between the amplitude of the piezoelectric vibrator under the asymmetric materials clamping and the materials of the clamping blocks was investigated.The results show that when the ratio of the elastic modulus of the clamping blocks materials is within a certain range,the difference in the amplitude of the displacement at the tip of the vibrator increases with the increase of the ratio of the elastic modulus.Finally,in order to discuss the second harmonic component appearing in the COMSOL simulation result,an experimental test was performed on the piezoelectric vibrator under the asymmetric materials clamping.The test found that this second harmonic component is unavoidable and exists objectively in actual work.This vibrator shows that the COMSOL simulation results are more accurate and closer to the actual situation than the dynamic model.2.Research on Linear Piezoelectric Inertial Actuator with Asymmetric Materials ClampingA linear piezoelectric inertial actuator with asymmetric materials clamping was designed and manufactured,and an experimental test system for the actuator was built to test its performance.The results show that the first-order resonance frequency of the actuator prototype is 13 Hz,and the range of working voltage is 15 V ? 45V;when steel and copper are used as the clamping block materials,the actuator prototype has the best stability and repeatability,a no-load resolution of 2.0?m,and the maximum carrying capacity and power consumption in non-resonant and resonant states are 40 g,90g,1.31 m W,and 3.31 m W,respectively.3.Research on Linear Piezoelectric Inertial Actuator with Asymmetric Clamping at Both EndsIn order to reduce the actuator backlash rate and achieve continuous adjustable friction,a linear piezoelectric inertial actuator with asymmetric clamping at both ends is designed and manufactured,the dynamic model of the actuator was established,and the simulation analysis was performed using Matlab/Simulink;an actuator experimental test system was set up to test its performance.The results show that when the excitation signal is 25 V,7Hz,and the magnetic field strength is 19.5mT,the backlash rate is 0.92,and the step resolution is 0.1?m of the actuator prototype;when the magnetic field strength is adjusted to 8.4mT,the backlash rate is 0,the step resolution is 2.53?m,and the simulation calculation results are in good agreement with the experimental results.The research shows that after the introduction of the magnetorheological fluid friction control unit and the piezoelectric bimorph is fixed at both ends,the proposed actuator can realize the continuous adjustment of the friction force,the backlash phenomenon is effectively controlled and the resolution is improved.