What Is an Ultrasonic Motor?
An ultrasonic motor is a type of motor that utilizes ultrasonic vibrations to produce rotational or linear motion. Unlike conventional electric motors, ultrasonic motors operate without direct contact between rotating or moving parts. This unique mechanism, involving the transmission of ultrasonic vibrations, results in virtually noiseless operation, making these motors ideal for use in acoustically sensitive environments or in equipment where quietness is essential.
Ultrasonic motors offer rapid motion due to high-frequency vibrations, suitable for applications requiring quick position control and high-speed motion. However, their application is generally limited to small devices. They may require careful design and load evaluation when used for large loads or high torques.
Uses for Ultrasonic Motors
Ultrasonic motors are used in various applications:
1. Optical Equipment
In optical equipment like cameras and video cameras, ultrasonic motors are employed for automatic focusing and zooming. Their high-speed response and quiet operation are advantageous for adjusting focal distances and lens sizes with high precision and smooth motion.
2. Medical Equipment
These motors are integral to medical devices such as endoscopes and echo imaging devices. Attached to endoscope tips, they enable fine positioning and vibration control, aiding in precise medical procedures and examinations. Their non-contact, silent nature is vital for patient comfort and effective treatment. Ultrasonic motors are also useful in MRI peripherals due to their immunity to magnetic forces.
3. Robots
In robotics, particularly in robot arms and manipulators, ultrasonic motors are chosen for their precision and fast response, essential for fine motion control and positioning in various robotic applications, including industrial and medical robots.
4. Electronic Products
Consumer electronic products such as smartphones and tablets often incorporate ultrasonic motors to provide touch feedback and vibration alerts.
Principle of Ultrasonic Motors
Ultrasonic motors typically operate based on the piezoelectric effect, using materials like ceramics or piezoelectric crystals. When the voltage at the drive frequency, matching the element’s inherent vibration frequency, is applied, the piezoelectric element undergoes periodic expansion and contraction. This deformation produces ultrasonic vibrations, which are then converted into rotational or linear motion within the motor.
Structure of Ultrasonic Motors
The typical structure of an ultrasonic motor includes:
1. Transducer
The transducer generates ultrasonic vibrations, providing the driving force for the motor, often using piezoelectric elements.
2. Driver
This component receives vibrations from the transducer, amplifying and converting them into motion. The driver can take the form of a rotating shaft or a slip ring for linear motion, often interfacing with a piezoelectric element or another amplifying component.
3. Rotor
The rotor, driven by the driver, executes the rotational motion. It is typically a rotating shaft or disk.
4. Stator
Contrasting the rotor, the stator controls the rotational or linear motion. It receives vibrations from the transducer or driver and provides the necessary force or constraint.