Research On The Beat Traveling Wave Theory Of Rotating Ultrasonic Motor And Its Application In Vibrating Motor

The traveling wave rotating ultrasonic motor is the most widely used and most mature ultrasonic motor(USM).It uses the inverse piezoelectric effect of piezoelectric ceramics to stimulate the vibration mode of the stator elastomer,so as to form a traveling wave in it,and thus produces a micro-amplitude,high-frequency elliptical motion on its surface.Under the effect of the elliptical motion,the rotor is driven to rotate continuously by friction.The working mechanism of ultrasonic motor determines that it has the characteristics of fast start and stop response time,self-locking,no magnetism and high motion resolution,which is widely used in precision positioning,medical industry,aerospace and other fields.In this paper,a new driving method,which named beat traveling wave(BTW),is proposed based on the traveling wave principle.BTW is formed by the superposition of two standing waves with different frequencies,similar amplitudes and phase difference 90° in space.When operating,it has the characteristics of beat vibration and traveling wave,which is the origin of the name BTW in this paper.The BTW’s operating direction changes periodically,and the cycle is the inverse of the difference of the two-phase excitation frequency.In addition,it is proved by experiments that the motor can be used as a vibrating motor at the appropriate frequency difference.Compared with the electromagnetic vibrating motor,the motor will have the advantages of fast response time,self-locking,and no electromagnetic interference,so it will be quite competitive in the future artificial intelligence tactile feedback field.The main work of this paper is based on the traveling wave USM,design a vibration motor driven by the BTW and applied to mobile devices.Firstly,the theoretical model of BTW is proposed,and its operation characteristics and rules are revealed.Secondly,according to the theoretical model of BTW,the motion equation of particles on the stator surface is obtained,and the dynamic mathematical model of patting traveling wave stator is established.Then through the stator vibration test and the motor speed test,the theory of beating traveling wave is verified.Finally,a prototype of the vibrating motor driven by the traveling wave is designed.The motor has a novel structure,the piezoelectric vibrator will vibrate under the reciprocating driving force generated by the friction contact surface.In this paper,the vibration intensity produced by the prototype is measured by the amplitude of vibration acceleration.Experimental results show that the output vibration frequency and vibration intensity of the vibration motor can meet the needs of tactile feedback.