中文摘要：

利用环形定子的两个弯振模态交替工作的原理设计的一种驻波型步进式超声电机具有开环控制下无累积误差的特性。定子环弯振使定子上的驱动齿分别在两个工作模态下运动产生对转子的驱动力，定子齿与转子齿槽相配合实现步进定位，转子齿槽数决定电机步距角。分别对应于两个工作模态的两相正弦驱动信号经切换单元提供给电机，对不同电极扇区的激励控制电机转动方向，工作模态间的切换次数决定转动步数。原理样机转子齿槽数为72个，步距角为2．5°。试验结果表明电机运转稳定，没有失步现象。

英文摘要：

A standing-wave-type stepping ultrasonic motor using the alternative operation of two bending vibration modes on the stator has no accumulative errors without the feedback. The driving forces are made from projection motions on the stator in two modes separately. The cooperation between the stator and the rotor projections, the number of which determines the stepping angle of the motor, and realizes the motor positioning. Two-phase sinusoidal signals according to two mode frequencies via a switch unit drive the motor bi-direction stepping rotation. The prototype runs steadily without miss-step on trial. The single-step anguler displacement of the motor with 72 rotor teeth is 2.5°.