Design And Experimental Study Of Friction Variable Piezoelectric Stick-slip Actuator

This paper is based on the China Association for Science and Technology's "Young Talents Lifting Project" Project "Research on Mechanism and Suppression Method of Backward Motion of Piezoelectric Actuator"(Item No.2017QNRC001).With the rapid development of modern science and technology such as advanced manufacturing,microelectronics engineering,biomedical engineering,optical precision engineering and nanotechnology,the processing and measurement of operating objects are not limited to the macro scale,but also need to be micro-nanoscale operating.Multiscale objects of operation have greatly expanded the demand of researchers in various fields for nanometer-scale measurement and operating systems for large journeys.Piezoelectric actuators based on the stick-slip principle can meet the above requirements at the same time,and have attracted extensive attention from many scholars at home and abroad.By analyzing the research status at home and abroad,it is found that the existing stick-slip piezoelectric actuator can satisfy high-precision positioning and large-stroke motion,but the lower motion speed limits the performance of the stick-slip piezoelectric actuator.The analysis finds that retreat is an important aspect to limit the speed of the stick-slip piezoelectric actuator.As for the existing stick-slip piezoelectric actuator has retreat,the following work has been done in this paper:First,a variable friction isosceles trapezoid-type stick-slip piezoelectric actuator is proposed in this paper.The four-piece rectangular piezoelectric ceramic plates bonded in both sides of the flexible skew beam of the isosceles trapezoidal stator is used to make the driving foot drive slider,and the isosceles trapezoidal stator can increase the static friction force of the "sticking" stage of the advancement of the slider and decrease kinetic friction force of the "slip" stage and suppresses retreat and increase output speed.The structure and motion principle of the proposed isosceles trapezoid-type stick-slip piezoelectric actuator are described in detail.The angle of the isosceles trapezoidal stator is optimized and the stress,strain and mode shapes are analyzed by finite element method.An experimental system was established and a series of experiments were carried out.The results indicate that the maximum output velocity is 601.803 ?m/s,and the maximum horizontal output force is 2.8 N,the maximum stable vertical load is 400 g,the minimum stepping displacement is about 0.026 ?m in the locking force of 4 N.From the analysis of the structure of the variable friction isosceles trapezoid-type stick-slip piezoelectric actuator and experimental data,it can be found that there are two shortcomings in the piezoelectric actuator.One is that the retreat has not been completely eliminated,the other is that the y-direction(positive pressure direction)displacement which is used to suppress the retreat increases the risk of energy consumption and wear,and also limits the maximum output speed of the piezoelectric actuator.Then the causes of these two shortcomings are analyzed,which provides a basis for the follow-up improvement.Secondly,according to the two shortcomings of the variable friction isosceles trapezoid-type stick-slip piezoelectric actuator,a flexible mover type piezoelectric stick-slip actuator was further proposed and developed.The working principle of the flexible mover type piezoelectric stick-slip actuator is elaborated and a series of experimental tests are carried out.With a 4 N locking force,the maximum output speed is 3218.79 ?m/s,the maximum horizontal output force is 1.1 N,the maximum stable vertical load is 400 g,and the minimum step distance is 0.055 ?m.The results show that the flexible mover makes full use of the waste y-direction displacement of the variable friction isosceles trapezoid-type stick-slip piezoelectric actuator,so that the newly proposed flexible mover-type stick-slip piezoelectric actuator can increase the static friction force for advancing the slider and reduce the basis of the retreating dynamic friction.In the above,the wear between the stator and the flexible mover is reduced,and the output speed is increased.In this paper,the research on the variable friction type piezoelectric stick-slip actuator has certain reference value for the stick-slip actuator in suppressing the retreat and improving the output speed of the driver.