A compact multi-degree-of-freedom piezoelectric motor with large travel capability

This study introduces a novel multi-degree-of-freedom (MDOF) piezoelectric motor (PEM) for high precision and a 10 × 10 mm2 large travel range within a rigid and compact structure (33 × 33 × 30 mm3). The motor consists of four piezoelectric tubes (PTs) arranged and mounted parallel to each other to enable controlled movement along both the X and Y axes by using a sawtooth waveform with a time-delay control strategy. The design features a moving plate clamped between two upper and two lower sapphire balls, with the balls supported by CuBe springs, ensuring symmetric and precise movement. Applying individual driving signals to each PT induces bending deformation sequentially in the same direction, followed by simultaneous recovery to the original position, thereby enabling the movement of the moving plate. Experimental results demonstrated that the motor operated effectively at a signal frequency of 150 Hz, with a minimum driving voltage of 18 V required for detectable motion. The motor exhibited the capability to produce step sizes from 0.53 to 6.23 µm with a linear relationship between driving voltage (±30 to ±180 V) and step size, ensuring consistent performance. The hysteresis analysis revealed minimal energy loss, with hysteresis ratios of 5.2% on the X axis and 4.16% on the Y axis, indicating the motor's high precision and efficiency. Additionally, the motor sustained a load of 120 g while traversing a 10 × 10 mm2 area, and continuous operation for 12 h revealed no significant performance degradation. The compact and reliable design of this novel MDOF PEM holds potential for applications in confined spaces, such as small-bore superconducting magnets, enabling precise large-area atomic resolution imaging and magnetic property measurements.