Search

A novel configuration of composite of Terfenol-D and stack PZT actuator is proposed for coil-free magnetic force control. This magnetic force control is based on the inverse magnetostrictive effect of magnetostrictive materials whereby the stress resulting magnetic force is controlled by the voltage of the actuator. The advantages, zero power consumption to maintain constant of the magnetic force and small power supply are inherited from characteristics of piezoelectric material. In addition, the configuration of the composite without rigid structure to apply pre-stress is simple and compact compared with our conventional one. In this paper, the measurements of the magnetic force with different size of the magnets and pre-strain clarified the magnetic force is strongly dependent on bias magnetic field and prestress. Linear stepping motor and magnetic levitation taking the advantage of low power consumption to maintain the position of the mover or levitated yoke are also introduced with some experimental results to discuss the potential of the device for practical applications.

We investigate the machining properties of Iron-Gallium alloy for microactuator. Iron-Gallium is ductile magnetostrictive material with moderate magnetostriction ranging from 100 to 300ppm. The microactuator of Fe-Ga is expected to have advantages of simple configuration, low voltage driving, high robustness against external force and high temperature environment, compared with that of PZT. Here the rod of Fe-Ga prepared by FSZM technique was machined to distributed pillars of 1mm square by milling process. The comparison of magnetostrictions of machined and non-machined parts by strain gage confirms the strains different in pillars are inherited from the grain distribution and the milling process does not significantly deteriorate the material properties. The measurement of displacements by LASER Doppler vibrometer supports the validity of strain measurement. The success of the fabrication of the distributed pillars of 0.7 and 0.5mm square exhibits the potential of the milling process for Fe-Ga with high aspect ratio suitable for practical micro applications.

We have been proposing a magnetic force control method using the inverse magnetostrictive effect of magnetostrictive materials. With a parallel magnetic circuit consisting of iron yokes and permanent magnet, the magnetic force exerting on the yoke can be varied by the mechanical stress applied to the magnetostrictive material. The characteristics of the magnetic force, such as stress-sensitivity and range of the variation, are mostly dependent on the material properties of the magnetostrictive material. So far we have mainly investigated the magnetic force using Terfenol-D (Tb-Dy-Fe alloy) and demonstrated its usefulness in practical applications. Recently, Galfenol, Iron-Gallium is widely noticed for alternative for the Terfenol with several advantages. Even lower magnetostriction, it is superior to the Terfenol with high piezomagnetic constant, low hysteresis loss, high saturation and good machinability. In this paper, we investigate the potential of the Galfenol for the magnetic force control method which can enlarge the variation range of the magnetic force and increase the stress-sensitively. The formulation of the magnetic force and experimental results of fundamental material properties and magnetic force of the Galfenol and Terfenol clarifies the merits of the Galfenol inherited from high saturation and high piezomagnetic constant. The correlation between the piezomagnetic constant and bias field is verified, providing magnetic circuit design strategy to make full use of the material properties of the Galfenol for future applications.

A high sensitive and heat-resistive magnetic sensor using a magnetostrictive/piezoelectric laminate composite is investigated. The sensing principle is based on the magnetostrictive- and piezoelectric effect, whereby a detected yoke displacement is transduced into a voltage on the piezoelectric materials. The sensor is intended to detect the displacement of a ferromagnetic object in a high temperature environment, where conventional magnetic sensors are not useful. Such applications include sensors in engine of automobile and machinery used in material processing. The sensor features combination of a laminate composite of magnetostrictive/piezoelectric materials with high Curie temperatures and an appropriate magnetic circuit to convert mechanical displacement to sensor voltages and suppress temperature fluctuation. This paper describes the sensing principle and shows experimental results using a composite of Terfenol-D and Lithium Niobate to assure high sensitivity of 50V/mm at bias gap of 0.1mm and a temperature operating range over 200 °C.

This paper presents novel magnetic actuator and sensor devices with a magnetostrictive/piezoelectric laminate. Both actuator and sensor are based on the conversion of electric and magnetic energies of piezoelectric and magnetostrictive materials via mechanical coupling, thus the advantages of the piezoelectric material, low power consumption and high speed response, are reflected on both functions. Here, several devices, laminations of Tb-Dy-Fe alloys and PZTs with different geometries or properties integrated into a magnetic circuit, are fabricated and their capabilities of magnetic force controlling and displacement sensing are investigated.

The three-dimensional (3-D) image formation technique using confocal microscopy has allowed visualization of the 3-D chemical structure in small parts of the bio-body. However, the large-scale 3-D structure such as the distribution of chemical components throughout the whole body has not been shown. To allow such large scale visualization of the 3-D internal analysis technique for bio-body has been developed. The 3-D internal analysis method has three stages. In the first stage, sequential sections of a whole bio-body were made using the automatic precision microtome system. Although this system is that used for microscopy, the obtained sections were positioned on an adhesion tape for 3-D reconstruction. In the next stage, all sections were stained using a chemical or immunofluorescence technique for visualization of the chemical components. Each stained section was digitally imaged using a spectroscopic stereomicroscope with a CCD camera. The obtained 2-D digital images contained the spectroscopic information representing the chemical components. In the last stage, the 2-D digital images were reconstructed to produce a 3-D image. As a result, the distribution of chemical components in the whole bio-body could be visualized in 3-D. In this study, the distribution of protein in a whole rice grain was visualized using a 3-D image.

In an earlier paper by the authors, down-scaled devices for microparts handling utilizing an AC electric field boundary wave were proposed. Devices that instantly generate contactless microparts driving forces through electric field creation have been designed and fabricated. In a further attempt, the mechanisms behind microparts conveyance are here subsequently validated in experiments and simulations. Particles as micropart substitute are actuated. On a thin protecting insulation-film above a series of encased and insulated parallel field electrodes, particles become either triboelectrically or induction charged through the application of balanced multi-phase voltages. The created non-uniform traveling field-wave conveys the charged particles perpendicular to the electrodes confined in electric filed traps from electrode to electrode. A series of particle materials with diameters up to 400 micrometers has been examined; metal, glass, and plastic spheres showed the best performances. Simulations of the potential distribution underline the experimental findings on the electric panel and dots device. One further result, which could ave been shown by experiments, is the pre-oscillation of a moving particle caused by gravity.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A blazed holographic optical element (HOE) has developed with injection molding technique. It is able to function as a beam splitter and aberration generator for focusing error detection of optical pick up head for optical storage system. The die was made by 4 axis controlled ultra precision cutting machine using single crystalline diamond cutting tool We carried out fabrication error estimation caused by cutting and injection, and derived adequate tolerance budget. The efficiency of HOE defined y the product of 0th and 1st order diffraction efficiency was measured by knife-edge method. We attained high efficiency of 15.5 percent which is close to theoretical limit. The efficiency is about 1.5 times as that of conventional non- blazed HOE.

Micro mechanical parts and optical parts are fabricated through ultra precision cutting technique. The precision cutting technique has been considered to be inappropriate for micro parts fabrication of the micrometer order. Our ultra precision cutting technique with sub-micrometer cutting depth made it possible to fabricate 3D micro mechanical parts and micro optical parts. Following micro mechanical parts are fabricated: 10 micrometer shaft by lathe machining, 100 micrometer screw with 20 micrometer pitch thread, and 50 micrometer thickness lever made by stainless steel. Also it was able to fabricate micro optical parts such as holographic optical element with sawtooth cross section and pitch of 3 micrometer. The fabrication was carried out with newly developed ultra precision machine tool with X, Y, Z linear axis and one rotational axis using single crystalline diamond cutting tool. Those linear axis are controlled through hologram scale with 1 nm resolution. The fabrication process by precision cutting has proved to be faster and more precise compared to the lithography and etching method.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Magnetic Supported Intelligent Hand (MSIH) is a robot hand for precision automated assembly. This paper describes the conception of the MSIH and explains its structure, control system, functions and experimental system. The MSIH has a unique structure incorporating a magnetic-bearing wrist mechanism, in which a floating body, holding a work piece, is supported by controlled magnetic forces without any mechanical contacts. The MSIH has three major functions: 1) the advanced Remote Center Compliance function; 2) the precision-actuating function of all three translations and two rotations of a work piece; 3) the sensing function of forces, moments and displacements. The MSIH can achieve precise insertion operations in various levels and conditions automatically by selecting or combining these functions.