A novel spherical ultrasonic motor, composed of three built-in stators and a hollow spherical rotor, is developed and tested for the design of a compact multi-degree-of-freedom (multi-DOF) piezoelectric driven actuator. The novel pre-pressure regulating mechanism is used to adjust pre-pressure along the axial direction of the stators simultaneously and homogeneously, so as to ensure the stability of the motor output. Using finite element method, the admittance circle is obtained by frequency domain analysis, which can estimate the resonance frequency and electrical parameters of the motor, and the coordinated driving trajectories of the three stators at different tilt angles are predicted by transient analysis. After the fabrication of a prototype, the admittance characteristics of piezoelectric stator are tested by LCR digital bridge measurement unit. Meanwhile, the mechanical output speed is measured. The rotational speeds of X-axis, Y-axis and Z-axis can reach 29 r/min, 17 r/min and 16 r/min respectively when the frequency matches, which verifies the feasibility and rationality of the multi-DOF movement of the motor.

开发并测试了由三个内置定子和一个空心球形转子组成的新型球形超声马达，并设计了紧凑型多自由度（multi-DOF）压电驱动致动器。新颖的预压调节机构用于同时且均匀地调节沿定子轴向的预压，以保证电动机输出的稳定性。采用有限元方法，通过频域分析得到导纳圆，可以估计电动机的共振频率和电参数，并通过瞬态分析预测了三个定子在不同倾角下的协调驱动轨迹。原型制作完成后，用LCR数字电桥测量单元测试压电定子的导纳特性。同时，测量机械输出速度。当频率匹配时，X轴，Y轴和Z轴的转速分别达到29 r / min，17 r / min和16 r / min，验证了多自由度运动的可行性和合理性。马达。