新型单振子多自由度超声波电机

提出一种基于压电陶瓷平面内应变的多自由度超声波电机。该电机的定子由中空金属圆柱加工而成，圆柱的四周加工成4个互相垂直的平面，上面分别粘贴四片沿厚度方向极化的钛锆酸铅(lead zirconate titanate，PZT)压电陶瓷。利用压电陶瓷在垂直极化方向平面内的变形，激励定子绕Z轴的扭转振动模态，实现转子绕Z轴的转动；激励在定子中固有频率接近、振动方向相垂直的伸缩振动模态和弯曲振动模态，并通过振动的叠加使定子末端质点产生绕X轴或者Y轴的椭圆运动，实现转子绕水平轴的转动。采用有限元方法对电机的定子进行分析设计，建立电机样机实验系统并测定样机的振动特性及输出机械特性。实验结果表明基于压电陶瓷平面内应变的电机可以实现绕3个互相垂直轴的多自由度转动。

Development of a Novel Multi-degree-of-freedom Ultrasonic Motor With Single Vibrator

A multi degree-of-freedom (MDOF) ultrasonic motor using in-plane deformation of lead zirconate titanate (PZT) elements was proposed. The stator of the motor was made from a hollow metal cylinder. The outside surface of the cylinder was flattened on four sides at 90° to each other and four rectangular PZT plates were bonded on them. The PZT plates were polarized in thickness direction. By using the deformation in the plane perpendicular to the direction of polarization, the rotation around Z axis was generated when the torsional vibration around Z axis mode was excited. And the rotation around X axis or Y axis was generated by combining the longitudinal vibration mode and the bending vibtration mode. The finite element method was applied to design the stator geometry, and a prototype of the MDOF ultrasonic motor was produced. Vibration characteristics of the stator and load characteristics of the motor were measured. The results show that the motor successfully provides the MDOF motion around orthogonal axes.