Tokyo Tech News

Factory transport conveyer: magic carpet powered by ultrasonic radiation force


Published: August 18, 2014

Hand carts with wheels are widely used in factories, production line, and other such environments. In some circumstances air pressure levitation is used to eliminate the wheels and therefore direct contact with floor. However, pressure levitation requires bulky air compressors and piping systems.

Here, as an alternative to conventional methods of eliminating such wheels of transporters, Kentaro Nakamura and his colleagues at the Precision and Intelligence Laboratory have developed a flying plate utilizing ultrasonic vibration, which can convey a load like a 'Magic Carpet' levitating above the floor.

The device has a simple structure consisting of an aluminum thin plate with piezoelectric ceramic elements bonded onto the plate. Flexural vibrations are excited on the plate at a resonance frequency of around 22.4 kHz. Although the vibration displacement amplitude is only 10 micrometers, the plate levitates above the floor by several hundred micrometers due to the ultrasonic radiation force originated from the high intensity ultrasonic field in the gap between the plate and the floor. The vibrating plate was capable to bear a 1-kgf load in the experiment. In a prototype conveyer, four vibrating plates were integrated as shown in Fig.1. For smooth floors a total non-contact levitation force of several kgf was possible. The frictional force was largely reduced even when the plate was in contact with the floor for higher loads of over 10 kgf. From the results obtained in this study, a 320-kgf load could be levitated using 140 plates.

Fig. 1 Vibration plate (left) and the configuration of the flying plate (right).
Fig. 1 Vibration plate (left) and the configuration of the flying plate (right).


T. Ishii, Y. Mizuno, D. Koyama, K. Nakamura, K. Harada, and Y. Uchida
Plate-shaped non-contact ultrasonic transporter using flexural vibration
Ultrasonics, vol. 54, no. 2, pp. 455-460 (2014).

Contact information
Professor Kentaro Nakamura
Precision and Intelligence Laboratory
TEL +81-45-924-5052 FAX +81-45-924-5091