Published papers

An electro-conjugate fluid (ECF) is a kind of functional fluid, which produces a jet flow (ECF jet) when subjected to high DC voltage. It is known that a strong ECF jet is generated under a non-uniform electric field (e.g., a field with a pair of needle and ring electrodes (a needle-ring electrode pair)). This study introduces the ECF jet to develop a novel flexible robot finger. First, we propose a concept for a novel robot finger. The robot finger mainly consists of a bending actuator, an ECF tank and ECF jet generators, which could be a micro fluid pressure source of the robot finger. Second, we characterize each component of the robot finger (i.e., the bending actuator and the ECF jet generator). We investigate the influences of electrode parameters on ECF jet generator performance in order to design the finger prototype. Finally we clarify the characteristics of the robot finger. The length, the diameter and the mass of the robot finger are 34.2 mm, 12 mm and 3.8 g, respectively. The robot finger can generate a force of 0.28 N and bend approximately 70 degrees. (C) Koninklijke Brill NV, Leiden and The Robotics Society of Japan, 2012

An electro-conjugate fluid (ECF) is a kind of dielectric fluid which produces a powerful flow (ECF jet) when subjected to high DC voltage. The ECF jet is a promising micro fluid power source for actuators and sensors including micro motors, liquid rate gyroscope, etc., however, these applications are developed upon trials and errors because the theory of the ECF flow has yet to be fully established. In this study we introduce the Korteweg-Helmholtz equation to develop an ECF flow model. Then we hypothesize that the Coulomb force is the dominant factor of the flow, and is occurred by two causes: an inherent dominant charge of fluid and a charge injected from a sharp electrode edge. The hypotheses are proved by the experimental results in this study. (C) 2011 Elsevier B.V. All rights reserved.

Electro-conjugate fluid (ECF) is a kind of functional fluid, which produces a jet flow (ECF jet) when subjected to high DC voltage. It is known that a strong ECF jet is generated under nonuniform electric field, for example, the field with a pair of needle and ring electrode. This study introduces the ECF jet to develop a novel robot finger. First, we propose a concept of the robot finger which mainly consists of an ECF jet generator, a bending actuator and an ECF tank. The robot finger is driven by ECF jet, and integrated with a pump and a tank. Next, we characterize the ECF jet generator and confirm the effect of the variation of electrode gap and number of electrode pair on its performance. Finally, we investigate the characteristics of the robot finger. The length, the diameter, and the mass of the robot finger are 25 mm, 5 mm, and 3.8 g, respectively. The robot finger can move 27.8 mm in x direction and 26.7 mm in y direction at 3.1 s when ECF jet generator is applied at 6.0 kV.

直流高電圧の印加によって活発なジェット流を発生する機能性流体である電界共役流体をマイクロ液圧源として内蔵し，柔軟なゴムチューブにぜん動運動を発生させるミミズ型ロボットを開発した．また，有限要素法を用いてゴムチューブの構造を改善した．

A micro pump is one of the most essential components in μTAS. However, conventional pumping systems have some difficulties to be miniaturized because it requires a power source. In this paper, we propose a novel micro screw pump driven by electrostatic force. Since the electrostatic force becomes dominant in micro region, it may be an effective driving source for micro pump. We propose an electrostatic drive principle of a screw pump using three-phase AC input. The micro screw pump is composed of a stator having flexible printed dircuits and a screw covered with a PET sheet. The drive experiments confirmed the effectiveness of the proposed driving principle and successful pumping with the developed micro screw pump at a flow rate of 111.4 μl/s.

An electro-conjugate fluid (ECF) is a type of dielectric and functional fluid that generates a powerful jet flow when subjected to high DC voltage. Although a high voltage is needed to generate the jet flow, the current is quite low at several microamperes, resulting in a total power consumption of several milliwatts. Using this smart fluid, we can develop micro fluid-driven mechanical components without any bulky pumps. Also, it is clarified that the power density of the ECF jet is higher when the electrode pair is miniaturized; therefore, it is suitable for micro actuators. Here, we propose and fabricate three types of soft actuators with an antagonistic configuration: (i) micro artificial muscle cells, (ii) a McKibben-type micro artificial muscle actuator using the ECF effect and (iii) a micro finger actuator with two chambers to bend. The actuators basically consist of a silicone rubber tube covered with a fiber sleeve and a micro pressure source using the ECF effect. Next, we apply and integrate these actuators into a micro robot hand, driven with ECF jets. The driving characteristics of the micro artificial muscle actuator and the integrated micro ECF hand with ECF fingers were fabricated and experimentally investigated. The experimental results show that this ECF jet actuation is effective for driving soft micro hands. (C) Koninklijke Brill NV, Leiden and The Robotics Society of Japan, 2010

An electro-conjugate fluid (ECF) is a kind of dielectric fluid which produces a powerful flow (ECF jet) when subjected to high DC voltage. The ECF jet is a promising micro fluid power source for actuators and sensors including micro motors [4] [5], liquid rate gyroscope [8] [9] etc. However, these applications are developed upon trials and errors because the theory of the ECF flow has yet to be fully established. In this study we introduce the Coulomb force to develop an ECF flow model. Then we hypothesize that the Coulomb force is occurred by two causes an inherent dominant charge depending on each fluid and a charge injected from a sharp electrode. The hypotheses are proved by the experimental results in this study. ©2010 IEEE.

As the demand for multi degrees of freedom (DOF) system increases, it becomes more important for engineers to select an appropriate actuator. An ultrasonic motor is one of the promising actuators for multi-DOF system because of its advantages as direct drivability, high stationary holding torque, noiseless and quick response against input signal, however, the complexity of input wiring could be one of the problems for practical use. So this study proposes a novel driving method for multiple ultrasonic motors using a common line signal input. The method uses a superimposed signal, which has frequency components corresponding to the driving frequency of each ultrasonic motor. Because ultrasonic motors are driven by the natural vibration of stators, each motor only drives according to the corresponding frequency component of the common superimposed signal input. First we confirm the influence of the proposed method on the rotational speed of each ultrasonic motor. Then we controlled the rotational speed of each motor using the proportional controller, which operates the superimposed signal commonly inputted to each motor. (C) 2010 Elsevier B.V. All rights reserved.