Research On A Piezoelectric Stick-slip Smooth Driving Method Based On Ultrasonic Friction Reduction

Piezoelectric stick-slip driving technology has been widely researched and applied to many technique fields such as the in-situ micro/nano test,precision optical instrument because of the merits of the high positioning accuracy,large stroke,no electromagnetic interference,and so on.However,the output performance of the piezoelectric stick-slip actuator is deteriorated because of the saw-tooth similar displacement backward motion caused by kinetic friction force in the rapid deformation stage.The displacement backward motion has become the mainly problem,which limits the development of the piezoelectric stick-slip driving technology.In this paper,a sinusoidal wave with a micro amplitude and high frequency are coupled with the rapid deformation stage of a saw-tooth wave.The kinetic friction force between the stator and slider based on ultrasonic friction reduction is effectively reduced in the rapid deformation stage,and the displacement backward motion of the stick-slip actuator is restrained,and then the output performance of the actuator is abviously improved,a piezoelectric stick-slip smooth driving method based on ultrasonic friction reduction is proposed.The change state of the friction force between the stator and the slider of the stick-slip actuator driven by the traditional saw-tooth drive method is analyzed in this paper.The displacement backward motion of the stick-slip actuator is mainly caused by the kinetic friction force between the stator and slider in the rapid deformation stage.By analyzing the rod mechanical vibration theory of longitudinal vibration,torsional vibration and the bending vibration theory,the design scheme of ultrasonic vibration in the stator is obtained,and the working principle of the piezoelectric stick-slip smooth driving method is researched,and the realization mechanism of the smooth driving method is clarified,and then the realization scheme of the smooth driving method based on ultrasonic friction reduction is provided.The structure design and simulation analysis of the piezoelectric stick-slip actuator is developed.The first order longitudinal vibration mode of the stator is the design core of the ultrasonic vibrition of the piezoelectric smooth driving method,and the modal simulation cloud of the stator is extracted,and the first order longitudinal vibration frequency is obtained.The ultrasonic friction reduction effect between the stator and slider is excited by the first order longitudinal vibration mode,and then the geometric parameters of the stator and the actuator is determined,and then the feasible implementation scheme of the smooth driving method is presented.The prototype of the rod type piezoelectric stick-slip actuator under smooth driving method is manufactured.The designed prototype mainly include a piezoelectric stack,a frictional rod,and a slider.The stator is consisted of the piezoelectric stack and frictional rod,and the mover refer to the slider in this paper.The cross section size of piezoelectric stack is 5 mm×5 mm and the length is 10 mm.The diameter of the friction rod is 4 mm,and the length is 40 mm.The prototype experimental test system is built.The experimental characteristics of the actuator under the piezoelectric stick-slip smooth driving method is carried out.The experimental condition is desgined as follows: The peak-peak voltage and frequency of the saw-tooth wave are 30 V and 300 Hz,and the peak-peak voltage and frequency of the sinusoidal wave are 6 Vand 39 kHz.Comparing with the traditional saw-tooth driving method,the displacement backward motion of piezoelectric stick-slip actuator excited by the smooth driving method is abviously restrained,and the effective step displacement is enhanced.The output velocity under the smooth driving method is increased by 147.24%.The load capacity using the smooth driving method is 2.88 times that of the traditional saw-tooth driving method,and the driving capacity is increased 89.56%.In addition,the presented method can effectively extend the symmetry working range of the actuator.At the same time,the designed stick-slip actuator by the smooth driving mothod method is effectively driven using the symmetrical driving signal(such as triangle wave),which have the regulation function of the driving signal.