Stick-Slip Tower-Shaped Piezoelectric Actuator

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 (<5 nm), 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 is 400 VP-P and the pre-pressure is 6 N. Velocity of the actuator reaches its maximum 1.2 mm/s at the frequency of 8 000 Hz and drops to its minimum 35 nm/s at the frequency of 1 Hz. 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 1 Hz and 300 VP-P during 1 cycle (200 ms), the actuator has a minimum stepping distance of 22 nm.