FIELD: radio engineering. SUBSTANCE: travelling wave motor is composed of stator with oscillatory body, excitation system incorporating assemblage of segments and exciting ultrasonic oscillations and rotor placed under pressure in contact with stator in surface region. It has sensor device placed on oscillatory body or on excitation system. Sensor device has three sensor surfaces which are installed on oscillatory body or on excitation system. Sensor surfaces are spatially displaced through λ/3 or through 3/4l, where l is length of travelling wave subject to excitation. EFFECT: improved functional characteristics. 7 cl, 9 dwg
