中文摘要：

超声马达是一种适合于真空环境中工作的理想驱动器，但其在真空下的特性研究较少。利用真空试验机和超声马达特性模拟实验台，分别在常压、低真空和高真空下测试了无磁型和普通型环形行波超声马达的转速和转矩特性。结果表明，两台超声马达的转速和转矩均随环境压强减小而减小；在真空下，普通型超声马达的负载特性较常态下差，无磁型超声马达负载特性受真空度影响较小，且优于普通型超声马达的负载特性。运用声悬浮和摩擦学理论初步分析了产生此现象的原因。

英文摘要：

Ultrasonic motor （USM） is one of the promising actuators that are utilized under vacuum conditions. There are a few studies on it in vacuum. Properties of rotational speed and torque of nonmagnetic and common ring type traveling wave ultrasonic motors in normal, low vacuum and high vacuum were studied respectively by using vacuum tester and simulating tester of USM＇s properties. It was found that both rotational speed and torque of the two USMs decreased as the environment pressure decreased. Under vacuum condition, the load properties of common USM were worse than those under normal condition. The load properties of nonmagnetic USM were affected a little by environment pressure. Nonmagnetic USM had better load properties than common USM. Acoustics suspension and tribology theories were applied to primarily analyze these phenomena.