中文摘要：

针对日常生活中常见的旋转一直线复合运动形式，提出新型的两自由度超声波电机．该电机由粘接压电陶瓷的变截面柱状定子和环状转子组成．电机通过单相方波电源供电，利用近谐振点惯性冲量的控制方法驱动转子运动．介绍电机的研究背景、基本结构和工作原理，利用ANSYS有限元分析软件建立定子的模型，对定子结构进行一定的优化设计．利用电机测控系统对原理性样机进行实验和分析．测试结果表明，通过控制输入方波的频率、占空比和幅值，可以有效地实现转子运动模式的切换、运动方向的改变和运动速度的调节．

英文摘要：

As rotary-linear motion is one of the most common forms of motion in daily life, a novel two degree-of-freedom （DOF） ultrasonic motor （USM） was designed based on the existing multi-DOF USMs. This motor consists of one single bar-type stator with variable cross-section and a ring-type rotor. The dual-mode motion can be obtained by the excitation of smooth impact drive method with single source square wave voltage input. The research background, motor structure and working principle were introduced successively, following with the optimization analyses based on ANSYS simulations on stator. A prototype motor was made and the characteristic measurements were taken. The experimental results show that the rotor can switch between rotary and linear mode smoothly by changing the driving frequency. The velocity and direction of the rotor motion can also be controlled reliably by controlling the amplitude and duty-cycle of input voltage.