A Self-Propelled Traveling-Wave Linear Ultrasonic Motor Based on End Excitation

Area of Science:

• Mechanical Engineering
• Robotics
• Materials Science

Background:

• Ultrasonic motors offer advantages in precision actuation, including compact size and high accuracy.
• Conventional traveling-wave linear ultrasonic motors require boundary constraints, limiting flexibility and self-propulsion.
• Existing designs face challenges in structural adaptability and autonomous operation.

Purpose of the Study:

• To propose and validate a free-boundary traveling-wave linear ultrasonic motor.
• To enable self-propelled motion without relying on external boundary constraints.
• To enhance the design flexibility and operational capabilities of linear ultrasonic motors.

Main Methods:

• A novel stator design with projection structures, piezoelectric ceramics for excitation, and damping material for energy absorption.
• Utilizing the B(3,1) out-of-plane vibration mode for improved performance.
• Employing finite element analysis to model and investigate vibration characteristics.
• Developing a new method using surface-attached piezoelectric ceramics to estimate the standing wave ratio (SWR).

Main Results:

• The proposed free-boundary motor successfully generates traveling waves without fixed boundaries.
• The B(3,1) vibration mode effectively enhances energy absorption and reduces SWR.
• Experimental validation confirmed a minimum SWR of 1.81, a no-load speed of 42.1 mm/s, and a maximum output force of 0.465 N.
• The novel SWR estimation method proved effective.

Conclusions:

• The developed free-boundary linear ultrasonic motor is feasible and demonstrates promising performance.
• The design overcomes limitations of conventional constrained ultrasonic motors.
• This work presents a new approach for designing flexible and self-propelled linear ultrasonic motors.