Research On Multi-DOF Spherical Piezoelectric Motor

With the development of science and technology,the requirement of miniaturization and high precision for driving devices is put forward in the field of precision machinery and high level equipment.The multi-degree-of-freedom piezoelectric motor based on piezoelectric technology has many advantages,such as high mechanical integration,convenient driving,high displacement resolution,free from electromagnetic interference and diversified motion output.It has a wide application prospect in precision optical instruments,medical equipments,and micro-robots.However,the availabled piezoelectric motor with the complexity of the stator becomes a major obstacle to miniaturization.In this paper,a new multi-degree-of-freedom spherical piezoelectric motor is proposed.In order to simplify the mechanism and lay the foundation for the miniaturization of spherical motor,the ring-beam structure and a spherical rotor holding by ring-beam structure is used to set the piezoelectric on the end of beam without partition.The main work of this paper is as follows:1.Based on annular stator type spherical piezoelectric motor with multi-degree-of-freedom and aimed at the problem of difficulty to miniaturize the annular PZT with polarized partitioned,a double-beam spherical piezoelectric motor with multi-degree-of-freedom is proposed.Each oscillator can excite multiple vibration modes.When two oscillators with the same structure can excite two working modes with similar frequencies,the spherical rotor achieves multi-degree-of-freedom motion under the effect of two working modes.2.Aiming at the problem that the working mode is covered by other vibration modes due to the processing and assembly errors,a four-beam spherical piezoelectric motor with multi-degree-of-freedom is proposed.It can avoid the interaction between working modes through single oscillator excites single mode.The structure consisted of two stators and one spherical rotor holding by two vibrators is easy to apply and adjust the pre-pressure.3.A prototype of the four-beam spherical piezoelectric motor is fabricated.The mechanical characteristics of the spherical motor prototype are investigated by experiments.The results indicate that it can achieve the movement with two degrees of freedom.The start and stop time of the spherical motor is millisecond,so the motor has a characteristic of fast response;the speed of spherical motor is proportional to the driving voltage in a certain range,so it has a characteristic of convenient speed regulation;the spherical motor has high angular displacement resolution of 500?rad at 200V_pp and is expected to be used in high-end equipment and precision drive field.