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Ultrasonic motor

Principle and Features of Ultrasonic Motors

area illustration
robot illustration
Illustration of a robot with a dead battery

General motors

Power OFF

I can't hold my posture


High voltage, magnetic field environments

Power plant

Cannot operate properly


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Technology & Development

Piezo Sonic is developing applications that integrate motors and robotics.

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Introduction of Robot Development Business

Robot Business Photos

Piezosonic motor

Ultrasonic motors from other manufacturers

Stepping motor

DC motor

Available in magnetic field environment

Zero power and attitude maintenance

Power in the same size

Positioning accuracy

Lifetime (intermittent operation)



About 0.8Nm

About 0.05Nm

Institution ± 0.045°

Institutio ± 0.09°

Institutio ± 0.36°

Institutio ± 1.0°

6,000 hours (intermittent)

1,500 hours

5,000 hours

10,000 hours

stepper motor
Inside the stepping motor
Ultrasonic motor contents

Typical motors rely on electromagnetic force for rotation, making them unsuitable for high-voltage or magnetic field environments. Additionally, they lose posture control when power is cut. Ultrasonic motors offer a solution by operating without electromagnetic force, using ultrasonic vibrations instead for rotation. This makes them suitable for challenging environments and allows them to maintain position even without power.

DC motor contents
ultrasonic motor
dc motor

ultrasonic motor

DC motor

Stepping motor

I can hold my posture

Power OFF

Ultrasonic motor

robot illustration
robot illustration
Power plant

High voltage, magnetic field environments

Can operate normally

Piezo Sonic ultrasonic motors

Ultrasonic motor drive principle

Piezoelectric ceramics, which deform under applied voltage, are used instead of coils or magnets for rotational energy. The deformation is amplified by a metal stator, generating rotational motion on its surface. This motion is transmitted to the rotor via frictional force, causing rotation. The shaft, fixed to the rotor, transmits motor torque and rotation. Constantly generated frictional force allows the motor to maintain position even when de-energized and uncontrolled (high holding force), enabling backlash-free direct drive.

Piezo Sonic's ultrasonic motors offer significantly longer lifespan and increased torque compared to conventional ultrasonic motors. Through structural and material improvements, their service life exceeds twice that of conventional models, rivaling that of stepping motors. These advancements have been recognized with patents and prestigious awards such as the "Monozukuri Award" from the Japan Society for Precision Engineering in 2018 and the "Good Design Award" in 2019.

Features of ultrasonic motors

This area diagram focuses on the relationship between torque and speed for ultrasonic motors, DC motors, and stepping motors of the same size.

Compared to other motors, ultrasonic motors are characterized by low speed and high torque.

They can maintain high holding force even when uncontrolled by frictional force and have no backlash, making it possible to build direct-drive actuator systems without using gears.

This area diagram focuses on the relationship between position controllability and weight (lightweight) of ultrasonic motors, DC motors, and stepping motors of the same size.

Compared to other motors, ultrasonic motors are characterized by their light weight and high position controllability.

The light weight of the rotating part results in low inertia, and when the drive signal stops, the motor instantly comes to rest due to frictional force, enabling precise positioning. (Final positioning accuracy depends on the external sensor: encoder or potentiometer and the control controller.)

DC Motor

Stepping motor

Ultrasonic motors

Ultrasonic motors

Stepping motor

DC Motor

Comparison with competitive products

Advantages as an actuator

  • 1,Low speed and high torque

  • 2,High holding power when no power is supplied

  • 3,High responsiveness and controllability

  • 4,Compact and lightweight

  • 5,Quiet operation

  • 6,Hollow structure is possible

  • 7,Non-magnetic

Ideal for MRI environments and as motors for precision positioning robots

Torque measuring instrument
steering mechanism
active supporter
precision stage

Ultrasonic Motor Precision Stage

Compact conveying and indexing equipment

General conveyor system, compact XY conveyor system

Steering mechanism

Active supporter

Ultrasonic motor torque measuring instruments

Piezosonic motor application areas

Research institutes

- Compact, quiet, precision work -

Detailed examination
MRI medical equipment

Medical institutions

- Precision, Non-magnetic -


- Holding torque, precision -

Optical microscope
Walk photo with robot

Everyday life

- Support,Assistance -

Control method for ultrasonic motors

Digital signal control (USB application)

Digital signal control (USB application)

​Telephone inquiries


​Business hours


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Please feel free to contact us with any questions regarding product specifications or to request a quote. You can also purchase our products directly from Amazon.


Differences between ultrasonic motors and general motors

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