Omni-directional orientation analysis of a triplet-stator spherical piezoelectric motor system

ABSTRACT

Spherical piezoelectric motors (SPMs) represent a promising actuator technology applicable to the development of motion control systems with multiple degrees of freedom. However, few SPMs have made it successfully to market, as an effective and systematic rotor orientation analysis and manipulation technique has yet to be developed. This study thus developed a novel triplet-stator SPM design that integrates electrode configuration to excite lateral vibrations and offers two fundamental rotor orientations for each set of piezoelectric plates by changing the contact position between the rotor and stator. To accomplish omnidirectional orientations for the proposed SPM system, we present a systematic orientation analysis based on spherical coordinates. We further apply the concept of vector composition to derive new composite orientations by adjusting the magnitude ratio of the provided torques between three stators. An orientation angle representation accounting for the rotor dynamics is used to validate the correctness of the synthesized orientation vectors both in simulation and experiments. The orientation analysis results in a three-dimensional sphere containing eight vector spaces corresponding to eight stator actuation modes, in which an arbitrary rotor orientation reference command can be generated under the designed actuation modes. Experimental results were well correlated with simulations, thereby verifying the effectiveness of the proposed SPM system design and orientation analysis.

GRAPHICAL ABSTRACT

KEYWORDS:

• Multi-DOF motion
• spherical piezoelectric motor
• vector composition
• omnidirectional
• orientation manipulation

Acknowledgments

The authors would like to thank the National Science and Technology Council, Taiwan, for providing financial support for this research under grant number MOST-111-2628-E-011-011. The authors would also like to express their sincere gratitude to Prof. Yu-Hsi Huang for providing a software tool to measure rotor speed and orientations.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary Material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/23080477.2024.2372926

Additional information

Funding

The work was supported by the National Science and Technology Council.