High-Power Electrostatic Motor

Keywords: Electrostatic force, Electrostatic motor, Electrostatic actuator, Linear motor, FPC, Film motor

Introduction

Nowadays, most of mechatronic devices employ electro-magnetic motors. However, recent progress of mechatronic devices requires more compact and powerful motors. To meet those requirements, we have been developing several types of high-power electrostatic motors. Among those high-power electrostatic motors, "Pulse Drive Induction Electrostatic Motor,"^[1] and "Dual Excitation Multiphase Electrostatic Drive"^[2] are introduced in this article.

Electrostatic Motor

One may surprise if he knows that electrostatic motor has longer history than electro-magnetic motor. The first electrostatic motor (Electric Bell, by Gordon, 1742) was developed in 18th century, almost one hundred years before the discovery of electro-magnetic force by Oersted^[3]. Then, several types of electrostatic motors had been developed until 19th century.

However, those electrostatic motors were very weak, and they required very high voltage for operation. Such characteristics had been prevented electrostatic motors from practical uses, and had made people believe that electrostatic motors are useless stuffs.

However, again, the situation has changed drastically in late 1980s. Micro electrosatic motors, which were fabricated using IC manufacturing process, attracted many researchers' attentions, and since then, many micro electrostatic motors has been fabricated up to now^[4,5].

Why do researchers of micro-motor prefer electrostaic motor rather than electro-megnetic motor? There are two major reasons as descibed in the following:

Electrostatic motor (or electrode) can be fabricated as 2-dimensional structure, whereas electro-magnetic motor (or coil) requires 3-dimensional structure. Therefore, we can easilly apply IC manufacturing process for electrostatic motor fabricatoin.
The force density of electrsotatic motor is estimated to get larger as its size gets smaller, whereas the force density of electro-magnetic motor is independent from its size.

This second reason leads us to such idea that we can obtain very strong electrostatic motor by integrating many small electrostatic-motor-elements. Based on this idea, some researchers are engaged in development of high-power electrostatic motors, and so we are. By utilizing Flexible Printed Circuitry (FPC) films, our developed electrostatic motors successfully recorded larger thrust force than other high-power electrostatic motors did.

High-Power Electrostatic Motor

In the following links, two types of high-power electrostatic motors, which we have developd, are introduced.

Pulse Driven Induction Electrostatic Motor

<--- Click them to read more --->

Dual Excitation Multiphase Electrostatic Drive

References

[1] S. Egawa, T. Niino, and T. Higuchi : "Film Actuators : Planar Electrostatic Surface-Drive Actuators", Proc. IEEE Micro Electro Mechanical Systems Workshop '91, pp. 9-14 (1991)

[2] T. Niino, S. Egawa, H. Kimura, and T. Higuchi : "Electrostatic Artificial Muscle : Compact, High-Power Linear Actuators with Multiple-Layer Structures", Proc. IEEE Micro Electro Mechanical Systems Workshop '94, pp. 130-135 (1994)

[3] The Institue of Electrostatics Japan: "Handbook of Electrostatics (in Japanese)", Ohm co. (1981)

[4] L. S. Fan, Y. C. Tai, and R. S. Muller : "IC-Processed Electrostatic Micro-motors", Proc. IEEE International Electron Devices Meeting, pp. 666-669 (1988)

[5] S. C. Jacobsen, R. H. Price, and J. E. Wood : "The Wobble Motor : An Electrostatic, Planetary-armature, Miroactuator", Proc. IEEE Micro Electro Mechanical Systems Workshop '89, pp. 17-24 (1989)

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