A 3-axis precision positioning device using PZT actuators with low interference motions

For expected applications of fast tool servo (FTS) and vibration machining, a 3-axis positioning device with low interference motions is proposed in this paper. The positioning device was composed of a XY stage and a Z-axis stage, which were actuated by piezoelectric (PZT) actuators combined with specially-designed symmetric flexure hinges. Through fundamental experiments, when the applied voltage was 50 V, the displacements along the X-, Y-, and Z-axes were measured as 6.35 μm, 6.61 μm, and 10.12 μm, respectively, with the corresponding small percentages of interference displacement of 3.80%, 4.02%, and 3.30%. In addition, the resonant frequencies were obtained as 1.06 kHz, 0.65 kHz, and 0.54 kHz. To examine control performances, a real-time control system considering hysteresis effect of PZT actuators was implemented by the field-programmable gate array (FPGA) modules to conduct tracing controls for sinusoidal waveform, 3D Lissajous motion, and 3D spiral motion. The tracing errors along 3-axis actuations were under 30 nm. The performances of a 3-axis positioning device were well demonstrated. Future work is to perform machining examinations on a machine tool.