An ultrasonic motor driven by the phase-velocity difference between two traveling waves

Area of Science:

• Mechanical Engineering
• Physics of Fluids
• Materials Science

Background:

• Ultrasonic motors offer advantages in precision and miniaturization.
• Controlling rotor speed in ultrasonic motors remains a key challenge.
• Existing designs often involve complex mechanisms for speed regulation.

Purpose of the Study:

• To present a novel ultrasonic motor design.
• To elucidate the operational principle based on wave dynamics.
• To experimentally validate the relationship between wave properties and motor speed.

Main Methods:

• Detailed description of a unique stator and rotor construction to generate traveling waves.
• Experimental measurement of wave dynamics using an in-plane laser Doppler vibrometer.
• Performance testing under varying load conditions.

Main Results:

• Demonstrated that rotor rotation speed is locked by the phase-velocity difference between stator and rotor traveling waves.
• Confirmed that the motor rotates to minimize this phase-velocity difference.
• Established that speed is primarily determined by phase-velocity difference within the motor's torque limits.

Conclusions:

• The novel ultrasonic motor design effectively utilizes wave dynamics for speed control.
• Phase-velocity difference is the critical parameter governing motor speed.
• The motor exhibits predictable performance, with speed independent of load up to maximum torque.