Design And Experimental Study Of Stick-slip Piezoelectric Actuator Based On Alternate Stepping Principle

Ultra-precision actuators are widely used in optical,optoelectronic engineering,microelectronics manufacturing,aerospace,ultra-precision machinery manufacturing,photolithography,medical research and other technical fields because of their fast response and simple structure.Because the output of a single piezoelectric element is minimal,the concept of step accumulation is proposed to achieve large strokes and high precision of piezoelectric actuators.Unlike other kinds of piezoelectric actuators,stick-slip piezoelectric actuators work effectively in terms of motion accuracy,motion velocity,and output force.The motion of the current piezoelectric stick-slip actuator in each cycle can be composed of two parts: the "stick" motion driven by static friction and the "slip" motion driven by sliding friction.Friction plays different roles in the two processes.In the slip stage,the friction is expressed as frictional resistance.It causes backward motion,which reduces the work efficiency and degrades the output performance.Most importantly,the actuator can achieve smooth motion if the backward motion of the slip stage is suppressed.In order to achieve smooth motion under no-load and horizontal loads,the paper has done the following work:First,an alternating stepping stick-slip piezoelectric actuator is designed to achieve smooth motion.Only one piezoelectric stack is used to achieve the effect of alternate stepping motion of the two flexure driving feet and to drive the slider in the positive direction of the x-axis.Then,the pseudo-rigid-body method,elastic beam method,and finite element method are applied to analyze the displacement in x and y directions.After machining the prototype,the test system is constructed.Through the sorting and analysis of the test data,the output characteristic curve of the slider is obtained.The designed actuator has exceptionally high adaptability.Switching between three motion modes(backward motion,smooth motion and explosive surge)can be achieved by adjusting the voltage.The designed actuator can achieve smooth motion without a load when the input voltage is between 20 V and 40 V.When the input frequency is 1300 Hz,the maximum speed of the designed actuator is 24.42mm/s.The resolution of the designed actuator under backward motion and smooth motion is 0.80 μm and 6.10 μm,respectively.Finally,to prove that the proposed alternate stepping principle is of universal significance for improving the stepping characteristics of actuators,a stick-slip actuator based on the biped cooperative drive principle was proposed in this paper.Flexible driving foot-B and flexible driving foot-A alternately push the rotor to rotate clockwise.Experimental results show that the stepping characteristics vary with the driving voltage,and the displacement curve transitions from non-smooth to smooth to sudden jump as the driving voltage rises.Furthermore,the displacement curves can maintain good smoothness within a horizontal load range of 20 g to 30 g.The maximum angular speed of the designed actuator is 1452 mard/s.To achieve the two core indicators of large stroke and high precision two stick-slip piezoelectric actuators are designed by using the method of alternating step.The designed actuator can achieve smooth motion under no-load and horizontal loads conditions,which has a certain reference function for the purpose of improving the output performance and efficiency.