BreakThrough Interview

Developing long-life ultrasonic motors and a robot that can travel over stepsPiezo Sonic Corp

<Part 1 (2 Parts in Series)>


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Piezo Sonic Corp is a fabless manufacturer(*) that develops business around two axes: ultrasonic motors, which attract medical equipment manufacturers, semiconductor production equipment manufacturers, and other manufacturers, and autonomous traveling robots for transportation that incorporates ultrasonic motors. Though the company was founded in 2017, it has won numerous awards, including the 2019 Good Design Award, for its proprietary "Piezosonic Motor," an ultrasonic motor product that Kohei Tada, President of the company, has been researching for more than 20 years. The company also specializes in manufacturing through industry-academia-government collaboration. How does it create new value? In this two-part series, we will look at the secrets behind its achievements.
*: Refers to a manufacturer that does not have its own factory.

Achieving the service life twice as long as that of conventional ultrasonic motors

”Piezosonic Motor,” winner of the 2019 Good Design Award and many other awards

Ultrasonic motors generate vibrations in the ultrasonic range by applying a voltage to piezoelectric ceramics. Then they convert the vibrations into rotational force and rotate using the frictional force generated between the metal stator and the rotor. Unlike DC motors and stepping motors, they do not use magnets or coils. This is the most significant feature, enabling them to operate normally even in high magnetic field environments such as in MRIs, which are indispensable in the medical field. They have various other strengths, such as high holding power to maintain their posture even when not energized, high torque, etc.

"One disadvantage of ultrasonic motors is that since they are powered by frictional force, the material can wear out quickly, which means that their lives are short. Our "Piezosonic Motor" improved on this disadvantage."

The product achieved a service life twice or greater than that of conventional ultrasonic motors. Further, it is 25% smaller in size than conventional products and weighs only about 250 g. Despite that, it demonstrates a maximum torque of 1.2 Nm (Newton meters) and a maximum rotational speed of 180 rpm, both of which are about 20% better than conventional products. In addition to its excellent quietness, its ability to achieve "slow rotation" is also exceptional.

"In fact, it is more difficult to move motors slowly than to rotate them at high speed. Many motors do not guarantee rotational speeds of 10 rpm or less for this reason; however, the Piezosonic Motor can control the rotational speed at 1 rpm or even slower.

With these features, the product is now being prototyped and implemented in medical equipment such as for MRIs as already mentioned, position control mechanisms in semiconductor production equipment, drive motors for EVs, etc. Above all, Mr. Tada has the highest expectations for implementing this motor in robots, the company’s other axis.

Developing an autonomous mobile robot for transportation that can travel over steps

The "Mighty" model #2, upgraded from the first model.

The company's long-term goal is to develop an assistance robot. There is a story that Mr. Tada's research on the best motor for robots led him to the Piezosonic Motor. The first step toward this goal was the development of an autonomous mobile robot for transportation called "Mighty.” It is a compact robot that is capable of transporting cargo of up to 30 kg over short distances. It uses RTK(*) positioning, which is more precise than GPS, Lidar(*2), and image sensors to achieve accurate autonomous traveling.

"Its remarkable feature is that it can travel over steps of up to about 20 cm. Most of the robots in the world can only move on flat surfaces. Unlike them, since "Mighty" can travel over curbs on the road, it can transport cargo from outdoors to indoors. We were granted a patent for this mechanism."

Another strength of this robot is its design, which allows highly flexible customization as each unit can be reconfigured, and therefore it can be combined with various service robots. For example, if we install a robot arm on it, it can perform work during transportation.

How were the "Piezosonic Motor" and "Mighty," both of which are promising for diverse applications in the future, created? In Part 2, we will explore behind the scenes of developing the two products and important points in collaborations that the company excels in.
*: Abbreviation for "Real Time Kinematic.” This technology achieves highly accurate positioning with an error of several centimeters, using the location data sent from a reference station set up on the ground.
*2: A sensing technology that uses laser light to detect the position and shape of objects accurately.

Series Combining the company’s own and other companies' technologies to create assistance robots

Series 1 Developing long-life ultrasonic motors and a robot that can travel over steps
Series 2 Combining the company’s own and other companies' technologies to create assistance robots

Company information

Piezo Sonic Corp

Kohei Tada, President

After working for an ultrasonic motormanufacturer, President Tada founded the company in 2017. The company is a fabless manufacturer that develops, manufactures, and sells Piezosonic motors, autonomous mobile robots, and IoT devices. Based on the knowledge of these products, the company also provides consulting services for developing new services.

Coverage date October 30, 2020

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