中文摘要：

提出一种基于3个行波定子的2自由度球形行波型超声波电机，给出了其结构及其驱动原理，重点介绍行波定子自动对心的自适应结构及其螺旋弹簧，该种结构可使每一个行波定子能柔顺地压紧球转子，可克服由3个行波定子的加工及其安装误差对电机产生的影响，保证每个定转子接触圆周之间的预紧力比较均匀一致。同时，给出了该种2自由度球电机的机械特性计算公式，并以极小范数解为优化目标等手段，分析了此球电机的性能特点。研制的球电机样机球转子直径40mm，堵转力矩达0．12N·m，空载转速90r／min，且各方向性能较一致。此球电机具有结构紧凑、安装方便和性能优越的特点，可用于机器人手腕、CCD云台控制等许多场合。

英文摘要：

A novel type of 2DOF （two degree of freedom） spherical ultrasonic motor with three traveling-wave type stators was developed. Its structure and driving principle are introduced, especially a spiral form of the spring was presented The key issue of the self-regulation between the stators and the spherical rotor was solved, and the errors caused by processing and installation were overcomed by making use of the special-made spring. Ensured that the preload between the stators and the spherical rotor was more uniform and smooth. The mathematics model of the motor was established based on the Friction Drive Model, and the analytical expression of mechanical characteristics calculation was deduced. The features of the mechanical characteristics were acquired by make the minimum Euclidean norm as a target. The developed motor has Ф40 mm rotor, the maximum output torque reaches 0.12N·m, the maximum speed is 90 r/min, and the performance is consistent in all directions. This type spherical motor has many advantages of compact structure, convenient installation, prominent performance. It has significant application in many field, such as robotics manipulator＇s joint, CCD working stage.