Toshiro Higuchi

Wall Climbing Mechanisms Using Electrostatic Attraction Generated by Flexible Electrodes

Electrostatic adhesion is evaluated for robotic wall climbing. To realize electrostatic wall adhesion, flexible electrodes were fabricated using plastic film and conductive foil. The wall adhesion performances were measured for conductive and non-conductive surfaces. The measurement results for a conductive surface revealed that flexible electrodes can work as a suction cup, and that both air suction force and electrostatic force can contribute to wall adhesion. A prototype robot using the flexible electrodes was fabricated, which could successfully climb up on a conductive wall with 6.6 mm/s. For adhesion to non-conductive surfaces, two additional methods were applied to the flexible electrodes, which are surface pre-charging and use of comb electrodes. The second prototype robot using the proposed methods could successfully adhere to a glass surface and could climb up with an average speed of 1.75 mm/s.

Three-dimensional measurement of ice crystals in frozen beef with a micro-slicer image processing system

Abstract A novel technique has been developed for measuring the three-dimensional (3-D) structure and distribution of ice crystals formed in frozen beef by using a micro-slicer image processing system (MSIPS). The system has functions to reconstruct the 3-D image based on the image data of exposed cross-sections obtained by multi-slicing of a frozen sample with the minimum thickness of 1 μm and to display the internal structure as well as an arbitrary cross-section of the sample choosing observation angles. The size and distribution of ice crystals can be determined from the 2-D quantitative information, such as the periphery and area of the crystals. The effects of freezing conditions on the morphology and distribution of the ice crystals were demonstrated quantitatively from the observations of raw beef stained by fluorescent indicator. For the samples frozen at −15xa0°C, the network structure of ice crystals were observed mainly at intercellular space, having approximately 100 μm in cross-sectional size, while that prepared at −120xa0°C showed the spherical crystals of 10–20 μm in diameter within the cells. The 3-D image of the sample demonstrated that the growth of ice columns was restricted by the intrinsic structure of muscle fibers. The proposed method provided a new tool to investigate the effects of freezing conditions on the size, morphology and distribution of ice crystals.

Three-dimensional measurement of ice crystals in frozen dilute solution

Abstract A Micro-Slicer Image Processing System (MSIPS) has been applied to observe the ice crystal structures formed in frozen dilute solutions. Several characteristic parameters were also proposed to investigate the three-dimensional (3-D) morphology and distribution of ice crystals, based on their reconstructed images obtained by multi-slicing a frozen sample with the thickness of 5 μm. The values of characteristic parameters were determined for the sample images with the dimension of 530×700×1000 μm. The 3-D morphology of ice crystals was found to be a bundle of continuous or dendrite columns at any freezing condition. The equivalent diameter of ice crystals were in the range of 73–169 μm, and decreased exponentially with increasing freezing rate at the copper cooling plate temperature of −20 to −80xa0°C. At the Tcp −40xa0°C, the volumes of ice crystals were in the range of 4.6×104 μm3 to 3.3×107 μm3, and 36 ice columns were counted in the 3-D image.

Evaluation of MR-compatibility of Electrostatic Linear Motor

This paper reports a new MRI (Magnetic Resonance Imaging) compatible actuator that can operate near an MRI without degrading its imaging quality. A high-power electrostatic motor is introduced and its MR-compatibility is examined, both experimentally and theoretically. The proposed motor was fabricated with only paramagnetic materials, and its MR-compatibility was evaluated by measuring the output performance of the motor and the signal-to-noise ratios of the MRI images. The experimental results showed that motor’s thrust force while positioned within the MRI is almost the same as that in normal operation. The signal-to-noise investigation indicated that the motor did not affect the MRI images when it was operated over 60 cm away from the MRI’s RF coil. The theoretical calculations showed that the magnetic field generated by the motor is relatively small and the effect of the MRI’s magnetic fields on the motor is negligible, suggesting that the motor is MR-compatible.

A 2-DOF electrostatic sheet conveyer using wire mesh for desktop automation

The present paper proposes an electrostatic actuator that realizes two-degree-of-freedom (DOF) motion of various sheet-like objects. The actuator utilizes electrostatic actuation technology based on induced charges. The technology can directly handle sheet objects, such as papers and plastic films with a particular surface resistance. The structure of the actuator is flat and thin, and thus it can be easily embedded on any desktop so that the desktop can have a function to physically interact with users. With the function, the desktop can be automated in such a way that it drives various objects on it to help users perform various desktop tasks. The prototype actuator presented here uses wire mesh as its electrode panel to realize two-DOF motion. The structure of the wire mesh and basic driving principle of two-DOF actuation are described. The challenge that arises when utilizing wire mesh panel is that actuations for objects can be sometimes coupled if there are multiple objects on the panel; for example, if we try to move only one object, the other objects nearby would move together unexpectedly. To solve this problem, the paper proposes a selective actuation technique that realizes handling of any one object with keeping other objects at rest

Development of a 2-DOF softness feeling display for tactile tele-presentation of deformable surfaces

This paper presents a 2-DOF controlled softness display and its application to a tactile tele-presentation system. It has been reported that softness feelings can be displayed by reproducing contact area, or contact width, on a fingertip. Several softness displays based on the contact area control have been reported in past studies, but all of them had only one degree-of-freedom (DOF) for their contact area control. Resultantly, the reproduced contact area was symmetric, which could only produce uniform surface feelings. In some practical deformable surfaces, however, the contact conditions are not uniform over fingertip surfaces; for example, if there is a small lump beneath a soft deformable surface, resultant contact area can become asymmetric. To reproduce such asymmetric contact conditions, a softness display should have more controlled DOFs. This paper reports our trial to realize a multi-DOF controlled softness display. As a first step, this particular paper describes a 2-DOF controlled display. The display has two DC motors which independently control both sides of the contact area. Resultant asymmetric contact area can facilitate, e.g., discrimination of lump location in soft deformable surfaces. The display was integrated into a tactile tele-presentation system together with a contact width sensor, which measures asymmetric contact condition. Using the tele-presentation system, discriminations of lump location are demonstrated.

Zero-Power Magnetic Levitation Using Composite of Magnetostrictive/Piezoelectric Materials

We present a zero-power magnetic levitation technique using a composite of magnetostrictive and piezoelectric materials. The composite is bonded to iron yokes with an attached permanent magnet, by which the magnetic force exerted on movable yoke via air gap is controlled by the applied voltage on the piezoelectric material. The magnetic force control is based on the inverse magnetostrictive effect of the magnetostrictive material, i.e., the magnetization is varied with mechanical stress. The advantage of the composite is zero power consumption, because no current flows in static operation as a result of the capacitive property of the piezoelectric material. This feature will be useful in high-precision stage or conveyor systems using magnetic levitation where heat generation and power consumption should be avoided. The zero power characteristic of the composite is valid at any reference gap or load, whereas that of the conventional electromagnetic type is valid only at the equilibrium gap. We performed two levitation experiments: one using the composite to demonstrate the zero power advantage, and the other combining the composite to adjust the bias gap and electromagnet to stabilize the motion of the levitated yoke. The composite driven by a small dc-dc converter successfully varied the gap and maintained it constant with zero power consumption.

High sensitive and heat-resistant magnetic sensor using magnetostrictive/Piezoelectric Laminate composite

A highly sensitive and heat-resistant 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 available. Such applications include sensors in automobile engines 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. This paper describes the sensing principle and demonstrates experimental results using a composite of Terfenol-D and Lithium Niobate to assure high sensitivity of 50 V/mm and a temperature operating range over 200/spl deg/C.

Micromagnetostrictive vibrator using a U-shaped core of iron-gallium alloy (Galfenol)

A micromagnetostrictive vibrator using a U-shaped core made of iron-gallium alloy (Galfenol) was investigated. The vibrator consists of a Galfenol core, with a 1mm2 cross section, a length of 5.8mm, and a 0.3mm separation between the prongs of the “U,” driving coils, and an iron yoke to close the magnetic loop. The Galfenol vibrator is superior to the PZT type in its high mechanical strength, low drive voltage requirements, and wide temperature operating range, and compared to our previous cylindrical type vibrator has a simpler construction and higher bandwidth. A displacement of 1.2μm (220ppm) was verified for the prototype with a 5.8mm long Galfenol core; the high magnetostriction >200ppm is inherited from the stress-annealed Galfenol. The displacement was also maintained under a 21MPa tensile stress (1.5kg hanging weight). Incorporation of a Nd–B–Fe magnet into the magnetic circuit successfully shifted the operating point to the linear portion of the magnetostrictive curves. This biasing effect is use...

Evaluation of an Electrostatic Film Motor Driven by Two-Four-Phase AC Voltage and Electrostatic Induction

This paper describes a voltage-induction type electrostatic film motor that operates by feeding electric power to the slider by electrostatic induction. In electrostatic film motors, feeding power to slider is important for better output capability and positioning performance. However, the power feeding using electric cables sometimes cause mechanical disturbance to the motor motions. In the new electrostatic motor, the power to the slider is fed by electrostatic induction, thus removing electric cables that can cause mechanical disturbances. The proposed motor has a two-phase electrode in the slider and a four-phase electrode in the stator. In addition, both stator and slider have the induction electrodes so that electric power is transferred to the slider through the induction electrodes. The paper first analyzes the thrust force characteristics of the proposed driving-electrode configuration, and then analyzes the characteristics of voltage induction, both based on capacitance-network analysis. The analyzed result is verified by experiments that showed good agreements with the provided analysis