Since stick-slip actuators present the advantage of allowing long displacements(several centimeters or even more)at a high speed with an ultra high resolution(<5nm),a new type of stick-slip piezoelectric actuator is proposed to attain sub-nanometer positioning accuracy.The actuator is composed of a slider and a tower-shaped stator using forced bending vibration in y-z plane to generate tangential vibration on the top of the driving foot.When excited by the sawtooth input voltage,driving foot of the stator is able to generate a tangential asymmetrical vibration on the top,and the slider is thus pushed to move.A prototype and its testing equipment are fabricated and described.Following that,the testing of vibration mode and mechanical characteristics as well as stepping characteristics are conducted.Experimental results show that under the condition that the sawtooth input voltage is400VP-Pand the pre-pressure is 6N.Velocity of the actuator reaches its maximum 1.2mm/s at the frequency of 8000 Hz and drops to its minimum 35nm/s at the frequency of 1Hz.When the excitation signal is the single-phase sawtooth stepping signal,the tower-shaped actuator can directionally move forward or backward step by step.And when excited by the sawtooth stepping signal with 1Hz and 300VP-Pduring 1cycle(200ms),the actuator has a minimum stepping distance of 22 nm.
本文回顾了压电尺蠖作动器的发展历史并重点介绍了一种LEF型大推力直线压电作动器,并对其工作原理和应用前景进行了详细的介绍。该型大推力作动器结构紧凑,具有大行程、大推力、断电自锁、耐磨的特点,其输出推力可达5.6 k N。该型作动器可应用于无人机中,通过该作动器来控制机翼的收缩,从而控制无人战机的速度,将显著提高无人战机完成作战任务的效率。
A novel linear ultrasonic motor based on d15 effect of piezoelectric materials was presented. The design idea aimed at the direct utilization of the shear-induced vibration modes of piezoelectric material. Firstly, the inherent electromechanical coupling mechanism of piezoelectric material was investigated, and shear vibration modes of a piezoelectric shear block was specially designed. A driving point's elliptical trajectory induced by shear vibration modes was discussed. Then a dynamic model for the piezoelectric shear stator was established with finite element(FE) method to conduct the parametric optimal design. Finally, a prototype based on d15 converse piezoelectric effect is manufactured, and the modal experiment of piezoelectric stator was conducted with laser doppler vibrometer. The experimental results show that the calculated shear-induced vibration modes can be excited completely, and the new linear ultrasonic motor reaches a speed 118 mm/s at noload, and maximal thrust 12.8 N.
A transient response model for describing the starting and stopping characteristics of the standing wave piezoelectric linear ultrasonic motor was presented. Based on the contact dynamic model, the kinetic equation of the motor was derived. The starting and stopping characteristics of the standing wave piezoelectric linear ultrasonic motor according to different loads, contact stiffness and inertia mass were described and analyzed, respectively. To validate the transient response model, a standing wave piezoelectric linear ultrasonic motor based on in-plane modes was used to carry out the simulation and experimental study. The corresponding results showed that the simulation of the motor performances based on the proposed model agreed well with the experimental results. This model will helpful to improve the stepping characteristics and the control flexibility of the standing wave piezoelectric linear ultrasonic motor.
