This paper represents the research finding of levitation and rotation control on bearingless motor with rectified circuit coil and inclined teeth. Rectified circuit coils are functioned as transmitting and receiving coil of wireless electric power transmission, and supply direct current to rotor coils. Rotor coils are used as rotor magnets not using permanent magnets. Even if horizontal force of magnet is strong, unless vertical force of magnet exists, a rotor does not levitate. So as to generate vertical force, the tip form of rotor and stator is made to incline and levitation force (vertical force) is acquired using this inclination.
A magnetic gear can transmit torque without contact by magnetic force. So it doesn't have wear, dust, vibration and noise. Therefore we don't have to use lubricant oil. In addition the magnetic gear has a torque limiter function. Many kinds of the magnetic gear are studied, but the magnetic gears have a demerit which the use efficiency of magnet is low. So surface permanent magnetic gears are studied because of their high magnet use efficiency and large transmission torque. However surface permanent magnetic gears are difficult to assemble. In this research, a prototype surface permanent magnetic gear which has the structure of only one layer with stackable structure is produced, measured the characteristic and examined, before producing the magnetic gear with multilayered structure. A new type magnetic gear is confirmed to be able to transmit the rotary motion through experiments.
Magnetic levitation technology, which can support an impeller without contact, is applied for durability and lifetime enhancement of an artificial heart. We have developed an artificial heart using a radial type self-bearing motor. The plus minus two-pole algorithm is adopted to levitate and rotate the rotor. Radial position of the rotor is controlled actively, and axial position of it is passively stable within the thin rotor structure. In this paper, new estimating equations of magnetic suspension characteristics were proposed in order to reduce the designing time and improve the calculation accuracy. Estimating equation of the magnetic suspension force which added the circumferential component of electromagnetic force and introduced square wave flux density distribution was developed. The estimating equation of the negative spring force was also developed. Calculation accuracy of the magnetic suspension force was improved by using the estimating equation of that. The estimating equations have the sufficient calculation accuracy that can be used for the design.
A novel 5-degrees of freedom (DOF) controlled magnetically levitated motor has been developed for paediatric ventricular assist device (VAD). The motor has a top stator, a bottom stator and a levitated rotor which is sandwiched by the both stators. A double self-bearing motor mechanism enhances a higher rotating torque production and realizes a 5-DOF active control of rotor postures. This paper investigated a magnetic suspension ability and rotation ability of two motors which are made of soft magnetic iron and powder magnetic core. The developed motor is 28 mm in diameter and 41 mm in height. The maximum energy efficiency is sufficiently increased from 46 % to 72 % by using the powder magnetic core motor, although the magnetic axial attractive forces are only slightly reduced by 10 % of the soft magnetic iron motor. The powder magnetic core motor has sufficient performance as an actuator of the paediatric VAD.
We have clarified that a magnetic-geared motor with permanent magnets in the high-speed rotor and stator slot shows a good performance in the output power and transmission torque. This paper describes the influence of the polarity of the permanent magnets in the stator slot on the torque characteristics. The torque characteristics are computed by using the finite element method and verified by carrying out measurements on a prototype.
In this paper, we propose an axially differential magnetic harmonic gear which has a high gear ratio compared with the conventional magnetic harmonic gear in spite of a small number of magnetic poles.The operational principle is described, and the effectiveness of this gear is verified by using 3-D finite element analysis.
In this paper, we clarify the difference between the efficiency of IPMSM (interior permanent magnet synchronous motor) driven by a position sensor and that driven by sensorless control. First, we investigate the effect of control parameters on the estimation error. The efficiency of an experimental motor driven by the sensorless control using the suitable parameters is a little lower than that driven by the position sensor. Moreover, the efficiency under control of maximum of (torque/current) is higher than 0.8 % through 5.1 % than that under control of (id = 0).
In this paper, a technique of magnetostatic field analysis for structural models with defect of arbitrary inclination angle is presented by adding a function obtained from conformal mapping to the approximate potential function based on the conventional FEM scheme. In this technique, geometry of the defect is not explicitly expressed on the orthogonal grid type FEM mesh but held as function within the analysis program. Since the change of the defect shape is reflected in that function, it becomes possible to use the original mesh without being changed. The magnetic flux density distribution around an inclined defect obtained by this presented technique showed good agreement with that from FEM analysis.
These days, there have been increased interests in wireless power transfer technologies. We have been studying printed spiral coils for wireless power transfer to improve the coupling coefficient between them. In this paper, we report coupling coefficients between two models of coils similar to the spiral coils. As a result, the calculated inner radius of the similar spiral coil with the maximum coupling coefficient agreed with those obtained from the experiment and electromagnetic field analysis. Therefore, we can design the spiral coil dimensions with the maximum coupling coefficient for various separations between them.
In recent years, Ultra wideband（UWB）attracts attention as a high speed and mass wireless communication technology in a short distance. In UWB communication, many UWB antennas have been proposed. In this paper, we propose a simple UWB antenna fed by a microstrip line towards building the antenna into edge spacing in an electronic equipment housing. As a result, at the UWB frequencies, the proposed antenna performed with VSWR less than 2.0 and good omni-directional radiation patterns.
An ultra-wideband (UWB) technology draws attention as a promising technology in order to materialize ubiquitous network. Considering a UWB radio communications system installed on small devices, such as mobile and wearable devices, from a view point of a cost, production, and miniaturization of devices, ultra-wideband antenna with a feeder line should be formed on a printed circuit board. In this study, a broadband dipole antenna with fan-shaped and trapezoidal elements with a microstrip feeder line, formed on a printed circuit board, was investigated. As a result, it was found that the antenna with the VSWR characteristics less than 2.0 and relative bandwidth of 110 % over the frequency band of 3.1 GHz to 10.8 GHz were obtained from the analyses and measurements.
Phantoms that imitate the electrical properties of a living body are widely used for various examinations. This paper reports an improvement in the electrical characteristics of a high-hydrous gel phantom by the addition of carbon microcoils and carbon fiber at a low-frequency band. This improvement occurred because the CMC and carbon fiber functioned as an inductance inside the high-hydrous phantom at a low-frequency band. The relative permittivity of a phantom with 2 wt% added carbon fiber was in good agreement with that of human muscle in a frequency range of 5 to 30 MHz.
In recent years, ultra wideband (UWB) technology has been drawing attention as a promising technology in order to materialize ubiquitous network. The third-generation (3G) and the fourth-generation (4G) smartphones which employ the UWB technology have been hot. This paper reports on a multiband antenna, which covers 800 MHz for 4G, 2.0 GHz for 3G and 3.1-10.6 GHz for UWB, built into such a smart phone. As the result of investigation, both of the multiband antennas, designed and made on an experimental basis, showed the VSWR less than 2.0 at 800 MHz, 2 GHz and UWB bands. In conclusion, the multiband antenna developed in this paper are enough in practical use.
Human body communication, which utilizes our body as part of the transmission medium, has received a lot of attention as a promising wireless technology for body area network such as communication in head-mounted wearable devices. In this paper, input impedance characteristics of transceiver electrodes, transmission characteristics and electric field distributions around the head model were investigated through an electromagnetic field analysis for clarify a transmission mechanism of human body communication between head-mounted wearable devices. The analysis results showed that the signal frequency had little effect on the transmission characteristics and electric field distributions in the frequency of 10, 20, 30 MHz. However, it was found that the transmission mechanism between head-mounted wearable devices is influenced by the number of electrode of transceiver. Moreover, impedance matched transceiver was designed for improving the transmission characteristics. These results suggest that the optimized transceiver can realize the human body communication with low-power consumption and low electromagnetic exposure for human.
Magneto-Acoustic Emission (MAE) is stress pulses observed during dynamic magnetization process of ferromagnetic material. The abrupt and discontinuous motion of 90° magnetic domain wall and rotation of local magnetization are considered as the major MAE sources. The characteristics of MAE depend on the applied stress because the stress influences the structure of magnetic domain. On the other hand, the MAE incidence is expected to be proportional to the magnetized volume in which the 90° domain wall motion and rotation of local magnetization occur. For actual engineering applications, it is important to clarify the correlation among the applied stress, the magnetized volume and the generated MAE. In this paper, we focus on the dependence of the MAE incidence on magnetization rate and examine the correlation for SM490A steel under several tensile stresses.
Eddy current testing (ECT) is one of the most representative nondestructive testing methods for metallic materials, parts, structures and so on. Operating principle of ECT is based on the two major properties of magnetic field. One is that alternating magnetic field induces eddy current in all of the conducting materials. Thereby, an input impedance of the magnetic field source, i.e., electric source, depends on the eddy current path. Second is that the magnetic field distribution depends only on the exciting but also the reactive magnetic fields caused by the eddy currents in targets. Former and latter are the impedance sensing and magnetic flux sensing types, respectively.<br>This paper concerns with an optimization of a new magnetic flux sensing type sensor named “∞ coil” whose exciting and sensing coils are composed of the ∞ shape and finite length solenoid coil wound ferrite bar, respectively. Optimization of this ∞ coil fully depends on the 3D finite elements methods. According to the 3D finite element simulation results, we have successfully carried out the optimum size of two exciting coils and a sensing coil.
Because magnetic particle testing (MT) can detect microcracks by a simplified method, it is applied in non-destructive inspections of ferromagnetic materials in various industrial fields. Recently, establishing a technology that quantitatively evaluates crack shapes as well as detects cracks with high-precision has become an important topic in the non-destructive inspection. We consider developing such a quantitative evaluation technique that employs magnetic particle pattern of a crack in MT. In this research, the process of magnetic particle adherence to a crack was observed with a high-speed video camera and the change in the magnetic particle amount was evaluated at each instant. In addition, the technique for evaluating small magnetic flux leakage (MFL) density accurately was discussed with the measurement and the numerical analysis. From these results, the relationship between the MFL density and the magnetic particle amount was evaluated.
This paper proposes a new magnetic-geared generator, which has a novel permanent magnet arrangement whereby the permanent magnets are embedded into the high-speed rotor and the stator slots, for direct-drive wind power generation systems. The prototype is described and the performance is verified by the experiment.
Damping property of a damper utilizing a magnetic particle assemblage in the presence of magnetic field is investigated experimentally. The damping force depends on installation angle of the damper in the absence of magnetic field. In our study, one or two electromagnets are arranged near the edges of the damper case and we have found that effect of installation angle of the damper becomes small in the presence of magnetic field in this configuration. Applying magnetic field by two electromagnets arranged near the edge of the damper is useful method to suppress asymmetric damping property due to the gravitational force acting on the particles.
Needle-like magnetic particles were added to magnetic compound fluids containing both 10 nm-size magnetic particles and several micrometer-size magnetic particles, and damping properties of these fluids were investigated experimentally by using a simple prototype damper. Damping force depends on the mixing ratio of three kinds of magnetic particles: 100 nm-size needle-like magnetic particles, 10 nm-size spherical magnetic particles and 1 micrometer-size spherical magnetic particles. Magnetic compound fluid containing needle-like magnetic particles behaves like a dilatant fluid basically even in the presence of magnetic field, while the fluid can be treated as a Bingham fluid or a pseudoplastic fluid in the presence of strong magnetic field.
A micropump is one of the most important microfluidic components in Micro Total Analysis System (μ-TAS) and Lab-on-a-chip. Conventional fabrication processes for micropumps are complex and laborious. Micro/nano-systems have been required to satisfy the integration, further miniaturization, and shortening fabrication process time for more complex application. In this paper, we propose a simple-structural micropump having a magnetically-driven diaphragm made of a photosensitive nanocomposite for an easy integration method. The fabricated micropump generated the one-directional fluid flow at the flow rate of 36.1nl/min evaluated by using image analysis with fluorescent microscope images.
Magnetic gears are a force transmitter consisting of permanent magnets. The mechanical input can be transmitted to an output shaft without contact by magnetic forces. The transmission property of the magnetic gears is usually better than that of mechanical gears, because it is free from transmission loss, mechanical friction, lubrication oil, dust, and ambient noise. However, in the analysis and experimental results is that there is a big difference has been reported. As one of the causes, in the analysis is considered that the actual movement of the magnetic gear has not been reproduced. Therefore, we have tried to do a detailed analysis of movement by calculating the torque from the results of magnetic field analysis. By solving the equations of motion from the torque applied to the secondary rotor, to calculate the position of the secondary rotor of next step, do the analysis in line with the actual movement of the magnetic gear. In this paper, we show the coupled analysis result of magnetic gear and effectiveness of 3D-BEM.
Linear DC Motors (LDM), used in office automation equipments (OA) such as line printers and image scanners, are required to be with high acceleration and fast-response. Under the condition of limited power supply capacity and an outside dimension, we investigate the structure of LDM to make the acceleration rise most quickly by using finite element method. In this paper, we examine the single-supported and double-supported LDMs. Target of acceleration, direct current and response time of acceleration are 490 m/s2, below10 A and 0.15 ms. As a result, double-supported LDM's maximum acceleration is 655 m/s2 and response time of acceleration is 0.36 ms, so the target is not achieved, but comparing to single-supported LDM, response time of acceleration is less than 0.59 ms.
This paper presents an application of unbalance compensation to a rotary gyro with hybrid suspension. In this gyro, a disk-type rotor is connected to a synchronous motor through a fluid bearing and the motor is fixed to the frame of the holder. The four-degree-of-freedom motions of the holder are constrained by a cross spring and a gimbal. The two rotational motions of the holder are controlled by four electromagnets. Such hybrid suspension makes the system less damped. Therefore, high-accuracy measurement is possible by this gyro. However, one of the problems is that an oscillating component due to unbalance appears in the estimated angular velocity because the estimation is based on the control currents for regulating the relative displacement of the holder to the stator. To solve this problem, unbalance compensation is applied to remove the oscillating component. It is confirmed experimentally that the estimated signal agrees well with the reference signal.
We studied the magnetic levitation system for an X-Y Linear Synchronous Motor(LSM). This system was used an X-Y LSM armature as a primary side, and 4 pole type yoke hybrid electromagnet was used for a secondary side. There are some advantages in using the magnetic levitation system for an X-Y LSM. It will be decreases friction and abrasion by making it noncontacting. In this paper, for stable levitation the magnetic levitation system, we analyzed the levitation force and static thrust of the this system.
Nowadays, most of the researchers have put a lot of effort in designing the permanent magnet type of linear motor. However, due to resource problem occur recently to the permanent magnet material has led to increment of the material cost. This situation made the linear motor productivity is reduced. Because of this reason, most of linear motor manufacturers are prefer to development non-permanent magnet type to ensure product competitiveness and increase cost performance. Therefore, in this research, a switched reluctance linear motor was designed. The teeth shape has been varied in order to observed the effect to it's performance. As a result, the best model of switched reluctance linear motor with optimum teeth shape has been proposed. The performance of the model also has been compared to other similar type of linear motor and the permanent magnet type of linear motor.
In recent years, the miniaturization of a linear motor has progressed by the chip mounter the miniaturization of a conveying machine, or the loading demand to a special use. There is a case where a smooth drive is required in it. It is important to take into account the influence of the Total Harmonic Distortion (THD) in the design of a linear motor. the THD of three magnet array were checked. At Halbach array which pursued high thrust density, the fundamental cause and effect relationship between the THD from fluctuating a Halbach array aspect ratio and the induction voltage was checked. At Cylinder Linear Synchronous Motor (CLSM) of small size (φ10) and high thrust density, I showed means to reduce the THD.
This paper provides the evaluated results of transmitting efficiency concerning about non-contact electric power transmission via a repeater antenna using magnetic resonance method under high-speed driving conditions. First, we evaluated transmitting efficiency in installing a repeater antenna between a transmitting antenna and a receiving antenna to fully understand the effects of the repeater antenna. Second, we also experimentally evaluated and simulated transmitting efficiency at zero velocity when the repeater antenna was installed in our own evaluation system. Finally, we found out that transmitting efficiency decreased at a peripheral velocity over 60 km/h when both a transmitting side rotor and a repeater antenna rotated at the same peripheral velocity.
An Fe-Cr single crystal film with Cr concentration gradient (0% - 13%Cr) was prepared by electron beam deposition and irradiated by 2.4MeV Cu2+ ions at 475°C. Irradiation effects on magnetization process were investigated using a Kerr microscope. Spike domains were observed at the boundary between irradiated and unirradiated regions, and the critical magnetic field where the spike domain disappears increased above the Cr concentration of 9%. This paper shows the usefulness of combinatorial study on irradiation phenomena and demonstrates a feasibility of magnetic nondestructive evaluation of the embrittlement in Fe-Cr alloys.
This paper presents two-degree-of-freedom motion control of a piezoelectric bimorph actuator with hysteresis compensation that does not use any external sensors. It has been demonstrated that the hysteresis characteristic can be reduced by the bridge circuit. However、 there is a problem to control the position and compensate for the hysteresis characteristics. This research work proposes a valid modelling method for hysteresis compensation and position control. Two-degree-of-freedom control is one of the robust control techniques that are effective for this actuator. It is a control system configuration that adds Linear Quadratic Integral control as a feedback controller to feed forward controller based on the inverse system. Experimental results validated both the control technique and the modelling method. However the experimental results used the values measured by external instruments. This paper proposes a control system configured to feedback the estimated value of the observer instead of the measured values by the external instruments. The experimental results show the effectiveness of the proposed control system configuration.
This paper represents torsional vibration control of a flexible manipulator. For torsional vibration suppression, the feedback control is designed based on Lyapunov's direct method. The feedback control of torsional motion of the flexible manipulator is derived by considering the time rate change of total energy of the system. If the both angle velocity and the angle of the manipulator are known, all the modes of the actuators can be controlled simultaneously. This approach has the advantage over the conventional methods in the respect that it allows one to deal directly with the system's partial differential equations without resorting to approximations. The numerical simulations are performed by using FILT (Fast Inversion of Laplace Transform) method of numerical algorithm and the effectiveness of the feedback controller is verified.
The purpose of this research is to develop a novel infusion pump using shape memory alloy (SMA) actuators. Conventional infusion pumps are used motors as a driving source. The pump is also commonly used as a blood pump. However, the motor causes noises and vibrations. In a medical field, these phenomena maybe give patients a discomfort feeling. Therefore, we focus attention on SMA actuators as the driving source instead of motors. SMA actuators have many advantages such as low mass, flexibility, small size and silent drive. In this paper, we report the driving principle, the structure and fluid transportation method of this pump. We also present as basic characteristic of the pumps.
It is known that shape memory alloy (SMA) is applied as actuator. Single SMA has a function as a sensor and an actuator. Moreover, it has small size, low mass and flexibility. However, there are some problems about heat dissipation for SMA actuators. We therefore focus on a cooling method using inert liquids. The SMA is driven by an electric current and then needs the insulation basically. Inert liquids have electric insulation properties and high heat transfer characteristic. The purpose of this study is to develop a cooling type SMA actuator using the inert liquids. We designed the cooling type SMA actuator and fabricated a prototype of it. In the results, we confirmed a cooling time was largely improved.
This paper reports experimental studies about anisotropy and attenuation as characteristics of ultrasonic propagation in a magnetorheological fluid (MRF) under AC magnetic fields. Parameters of this studies are magnitude of AC magnetic fields (50 mT), frequencies of AC magnetic fields (1, 2, 3 Hz) and angles between directions of ultrasonic propagation and magnetic field (0, 45, 90°). As results of change rate of sound velocity, MRF has characteristics of time dependence, frequencies dependence and anisotropy under AC magnetic fields. Also, length of clusters in MRF became short with increase of frequencies of AC magnetic fields. The clusters in MRF are formed along the magnetic force under AC magnetic fields. Attenuation decreased with increase of the angles between directions of ultrasonic propagation and magnetic field. But, attenuation did not change with increase of frequencies of AC magnetic fields.
The effect of magnetic field distribution on the micro processing for inner wall of a horizontal positioning pipe was investigated. The processing tool installed ring-shaped permanent magnets between spacers utilizing magnetic compound fluid (MCF) was inserted and rotated in the pipe. In the experiment, the characteristics of material removal, velocity distribution of magnetic clusters and pressure distribution on the inner wall were investigated using the tool with different structure. Relation between these characteristics and the magnetic field distribution was clarified. In the case of using the tool which can hold much MCF, the material removal follows as Preston's law, and thick and long magnetic clusters deform on the perimeter of the permanent magnet.
Electro-oculograph (EOG) is one of the biosignal that can be used to improve life quality in human machine interface area. EOG occurring as the eye activities changes the magnitude of potential between cornea and retina. This signal was used to control robot manipulator in four directions (up, down, left and right). To record this phenomenon we used NF Instrument with head box to amplify the signal and processor box to process digital filters. Combination of 3 digital filters, 1.6 Hz High Pass Filter, 60 Hz Low Pass Filter and 60 Hz Ham Filter and finalized by 6 Hz Low Pass Filter gave neat signal until the difference among the eye movements could be distinguished. This is a real time system since it could detect when a signal comes and send it to the robot manipulator system through Arduino microcontroller. The determination of the signal emersion was successfully calculated by the combination of wavelet transform with scale = 1 and translation = 0.31 and garbor filter with σ = 1. Since the average accuracy of the system is more than 90% so we can use this method for some extend applications later.
Magnetic properties of electrical steel sheet which is used motor cores are influenced due to mechanical stress. Therefore, it is necessary to know the magnetic properties under tensile, compressive and shear stress conditions in order to utilize the electrical steel sheet effectively. This paper presents the influence of the principal stress on vector magnetic properties of a non-oriented electrical steel sheet. The vector magnetic properties of the non-oriented electrical steel sheet are measured by changing the amplitude and angle of the principal stress to evaluate the stress effect of the motor core. From these results, it was clarified that the loci of the magnetic field strength vector and magnetic power loss depend on the amplitude and angle of the principal stress.
In order to clarify the iron loss distribution in iron core of electric machines, the magnetic field analysis considering 2-D vector magnetic properties is effective. Several kinds of modeling of 2-D vector magnetic properties are proposed, the complex E&S modeling is most simplified and is useful to optimal design of electric machines. 2-D vector magnetic properties used in analysis are defined by three parameters, the maximum magnetic flux Bmax, the inclination angle θB, and the axis ratio α. However we obtain the amplitude and the phase shift of magnetic flux densities when we calculate the finite element analysis which introduced the complex E&S modeling. Therefore we have to recalculate the three parameters from the amplitude and the phase difference of magnetic flux densities. In this paper, we define the amplitude and the phase difference of magnetic flux densities as parameters of the 2-D vector magnetic properties, carry out the finite element analysis which introduced the complex E&S modeling.
Currently, there are many systems to support people with disability in their day to day activities. In this research, a robot arm system was designed, developed and controlled by use of an EOG (ElectroOculography) signal generated by the eye movement. The first part of the research was to establish the relationship between gaze position and EOG signal. Using Helmert transform method, the gaze position is estimated. The average error between real gaze position and estimated gaze position was ±4 cm. To recognize blink through EOG signal, Bell phenomenon was used. The blink recognition (voluntary and involuntary) experiment includes three occupants. The overall success rate of recognition of their blinks was more than 90%. Using this system long will make operators tired and results in erroneous experimental results. Thus, the switch from “control on” to “control off” was introduced in this system. The switch is activated when voluntary blink is detected. This will allow the system to improve the controllability.
Motions estimation utilizing EEG can develop devices supporting the elderly and disabilities. This paper investigated a possibility of limb motion estimation using Bereitschafts Potential (BP). BP means voltage variation of EEG just before motions. To estimate, neural network was introduced. Three types of processed signal were used as the input. The types of signal processing were FFT, increment and normalization. The best signal processing of them was normalization, and the accuracy rate was 89.0%.
This paper presents a numerical modeling method of two-dimensional magnetostrictions on a non-oriented electrical steel sheet and a grain-oriented electrical steel sheet under alternating and rotating magnetic flux conditions. Non-sinusoidal magnetic flux occurs in a core of electrical machines due to excitation conditions and magnetic anisotropy. Therefore, it is not easy to estimate the magnetostriction under this magnetic flux condition. Principal magnetostrictions of expansion and contraction have been derived from the measured 2-D magnetostriction under sinusoidal magnetic flux conditions. In the suggested modeling method, the principal magnetostrictions have been modeled using the E&S model. Because, coefficients are expressed as waveform, it is possible to model the 2-D magnetostriction on two different kinds of electrical steel sheet. The 2-D magnetostriction under non-sinusoidal magnetic flux condition has been estimated using the suggested modeling. The estimated and measured magnetostriction were in agreement. Thus, the validity of the suggested modeling method was confirmed.