Papers by Hiroyuki Wakiwaka
Nihon Ōyō Jiki Gakkaishi, 2001
There are many requiremends for measuring torque, such as non-contact with the shaft, small size ... more There are many requiremends for measuring torque, such as non-contact with the shaft, small size of the measurment device, and simple installation. Other requirements include no special processing in the shaft and cost-effectiveness. Therefore, we have proposed three magnetostrictive-type torque sensors for a steering shaft using an inverse magnetostrictive effect.Generally, a magnetostrictive-type torque sensor for a low-carbon steel shaft has a large hysteresis to the torque and output fluctuation due to axis rotation (0-level fluctuation). In this sensor, we show that the hysteresis and the 0-level fluctuation on the output voltage can be drastically decreased.
Ieej Transactions on Industry Applications, 1994
Linear pulse motor (LPM) can be directly driven by the digital signals. However, a high accuracy ... more Linear pulse motor (LPM) can be directly driven by the digital signals. However, a high accuracy position ing system using LPM needs fine position information for feedback signal. There are the optical displacement
IEEE Transactions on Magnetics, 1996
We have developed a meander coil type linear sensor. When a detection coil is moved on a scale co... more We have developed a meander coil type linear sensor. When a detection coil is moved on a scale coil, mutual inductance fluctuates according to the displacement, causing the impedance change of detection coil. Therefore, displacement can be detected by using this impedance change. Impedance becomes like a sine wave form and impedance variation increases by resonating the coil, compared with the case when the coil is not resonating. When the width of the detection coil and scale coil are 0.5 and 0.6 mm respectively, impedance variation has its maximum of 38.6 Q .
Magnetic Material for Motor Drive Systems, 2019
In this chapter, small- and medium-sized linear motors used in the industrial field are considere... more In this chapter, small- and medium-sized linear motors used in the industrial field are considered, firstly classified into four types based on their operation principle, and their each features are described. Next, the method of characterizing the linear motor is explained, and some of the characteristic evaluation indexes are shown. Furthermore, in order to evaluate the characteristics of the linear motor, the relation between the thrust and the tangential stress is explained, and the traditional magnet array, the repulsion type array, and the Halbach magnet array are shown as the magnet arrangement in the case of permanent magnet field. In addition, recently developed several high-performance linear synchronous motors are classified into permanent magnet field type and variable reluctance type from the viewpoint of thrust source. Finally, the values of the motor constant square density of those synchronous motors are compared.
Journal of the Japan Society of Applied Electromagnetics and Mechanics, 2018
Journal of the Japan Society of Applied Electromagnetics and Mechanics, 2023
Journal of the Japan Society of Applied Electromagnetics and Mechanics, 2022
Journal of the Japan Society of Applied Electromagnetics and Mechanics, 2013
In our previous report, we proposed a magnetic shielding system for the calibration of high-sensi... more In our previous report, we proposed a magnetic shielding system for the calibration of high-sensitivity magnetometers. This system consists of inner hexagonal tubes and an outer cylinder. The hexagonal tubes have a doublelayered structure, an opening and an advantage in axial shielding performance. The cylinder has openings and an advantage in transverse shielding performance. Compared with conventional cylindrical shields, our system is not capable of equipping a toroidally wound coil which can be used for degaussing the magnetic layers. The purpose of this paper is to reduce the residual magnetic flux density with a degaussing coil. Instead of the outer cylinder, we design an outer hexagonal tube. A solenoid-like coil is installed between the inner and outer tubes to effectively provide a degaussing field to the magnetic materials. For practical use, we also take care of both the total weight and shielding performance.
IEEE Transactions on Magnetics, Oct 1, 2011
The purpose of this study is to demonstrate the energy harvesting of power line magnetic noise. T... more The purpose of this study is to demonstrate the energy harvesting of power line magnetic noise. To the best of the authors' knowledge, no research has yet been carried out to confirm this possibility. In this paper, we present a simple circuit design model, and confirm its validity by experimental results. For small self-sufficient devices in a wireless sensor network, the target energy level is 1 mW. We prepare an energy harvesting module with an air-core coil and resonant capacitor. From experimental and simulated results, we investigate the desired conditions for harvesting 1 mW from a uniform magnetic field of 60 Hz. Through experimental results with iron cores, the benefits and drawbacks of the use of a magnetic core are also discussed. With our best harvested module, we successfully demonstrated the energy harvesting of 6.32 mW from a magnetic field of 21.2 μT at 60 Hz. If the usable magnetic flux density increases 10-fold, the harvesting energy increased 100-fold. If the magnetic flux density is at an acceptable level in a public space of 200 μT at 60 Hz, the harvesting power density becomes 130 μW/cm 3. This value is comparable to the value of an energy harvesting module of a light source during a cloudy day.
Sensors & Transducers, Dec 1, 2010
Sensitivity limits of magnetometers with air-core pickup coils are considered through three basic... more Sensitivity limits of magnetometers with air-core pickup coils are considered through three basic principles, Faraday's law, the definition of inductance and Ohm's law. This paper presents two simple equivalent circuit models for voltage detection and current detection, and describes their sensitivity with eight parameters. Both models require different methodology for optimal pickup coil design. The calculated results are in agreement with experimental results, and illustrate the advantages of magnetometers based on current detection model.
IEEE Transactions on Magnetics, Jun 1, 2009
Stable operating conditions for a high sensitivity induction gradiometer are studied experimental... more Stable operating conditions for a high sensitivity induction gradiometer are studied experimentally. In order to reduce electrical interferences in our developed induction gradiometer, we construct a Faraday cage. It consists of copper mesh and wood, and is 2.0 m × 1.8 m × 1.8 m in size. Experimental results show that the inside of the cage can provide a quiet electrical environment where the electrical interference is suppressed. Choosing a suitable grounding point for the electronics, undesirable signals in the sensor output are cleaned. Observation of a weak magnetic field is also demonstrated.
Nihon Ōyō Jiki Gakkaishi, 1997
Nihon Ōyō Jiki Gakkaishi, 1997
Journal of the Japan Society of Applied Electromagnetics and Mechanics, Sep 10, 2009
The transactions of the Institute of Electrical Engineers of Japan.A, 2011
This paper presents an induction magnetometer with a metal shielded pickup coil for MHz range ope... more This paper presents an induction magnetometer with a metal shielded pickup coil for MHz range operation. The validity of two simple equivalent circuit models for voltage detection and current detection is also confirmed by experimental results. From the measured frequency response for a calibrated magnetic field of 10 nT, we successfully demonstrate the ability of the magnetometer. The experimental results reveal the quantitative data of the equivalent resistance and inductance. When the resistance of the pickup coil is quite low, the equivalent resistance can be regarded as the resistance of the BNC connector (50 Ω). With the equivalent resistance, the absolute error of the output voltage between measurement and estimation is less than ± 1 dBµV between 0.3 MHz and 2 MHz. In contrast, it is found that the existence of the metal shielded layer affects the estimated equivalent inductance. If the pickup coil has no metal shielded layer, the estimated value of the equivalent inductance is 56.3 times the inductance of the pickup coil. This value is verified by the estimated and measured results. However, this phenomenon is not found if the pickup coil has the metal shielded layer. キーワード：インダクション磁気センサ，電流検出型，微弱磁界，MHz 帯域，等価回路モデル Keywords：induction magnetometer, current detection type, weak magnetic field, MHz range, equivalent circuit model
Materials Science Forum, Aug 1, 2014
The relation between the Electro Motive Force (EMF) and Total Harmonic Distortion (THD) was compa... more The relation between the Electro Motive Force (EMF) and Total Harmonic Distortion (THD) was compared and verified by magnet arrangement. Using Halbach array, thrust was more increase by change of magnet arrangement. Moreover, the variable trend of cogging and THD by magnet ratio and magnet form change was checked.
IEEE Translation Journal on Magnetics in Japan, Nov 1, 1994
Sensor Letters, 2013
ABSTRACT The objective of this study is the development of a magnetic sensor with a simple config... more ABSTRACT The objective of this study is the development of a magnetic sensor with a simple configuration, which can detect weak magnetic fields in the MHz range. This magnetometer consists of an air-core pickup coil and a transimpedance amplifier. When a magnetic flux crosses the pickup coil, a current is induced. The amplifier converts the current to a voltage signal with a transinpedance gain. A one-turn coil is suitable for the pickup coil. The resistance and inductance of the coil are easy to estimate, and the parasitic capacitance can be quite low as compared with a usual multi-layered coil. From the experimental results, we successfully demonstrated the operation of the magnetometer in the MHz range. With a transimpedanse gain of 60 dB, the magnetometer exhibited a linear response in the frequency from 300 kHz to 5 MHz, and the output voltage was 76 dB mu V for a magnetic field of 10 nT. The estimated noise floor level was as low as 1 pT/Hz(1/2). According to the noise floor level, the detection of the field less than 1 nT is possible with the bandwidth of 10 kHz. If we use narrow bandwidth for measurement and a higher transimpedanse gain, it could detect a field as low as fT order.
Nihon Ōyō Jiki Gakkaishi, 2003
This paper describes with a new linear synchronous motor (TFIP-LSM) of a transverse flux and inte... more This paper describes with a new linear synchronous motor (TFIP-LSM) of a transverse flux and interior permanent magnet type, which consists of an interior permanent magnet stator and a mover with a claw pole structure. The dimensional parameters of the motor and the electric efficiency were taken into careful consideration, using FEM simulations and measured values. In recent years, LSMs have been used for semiconductor product equipment, mechanical devices, and chip mounters. The trend has been to conduct research on high-efficiency miniature LSMs. To estimate the performance, thrust density Fv (N/cm3) and thrust constant density G (N2/(W cm3)) have recently been used. Within the last two years, LSMs with G = 0.66−5.1 N2/(W cm3) have been developed. TFIP-LSM is small compared with other LSMs and its thrust density motor constant is also small but the thrust constant density of 2.4 N2/(W cm3) indicates that a high performance has been obtained.
Uploads
Papers by Hiroyuki Wakiwaka