We propose a biped locomotion system that its gait is changeable in real-time. Our targets are; artificial leg, slave machine, remote-brain home-robot, etc. Our dream is to develop new transportation tool that rider can control its gait. We call this imagination as “Biped Bike.”
In this paper, we discuss the way of real-time gait control of biped locomotion. We propose Virtual Inverted Pendulum (VIP) Method for controlling the walking speed. This method considers the continuity of biped walking especially on transient status such as acceleration and deceleration. The actual biped system is made and real-time gait control is realized using VIP method.

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It is desired to develop soft-switching power factor improvement technology and put it into practical use by means of a high-efficiency, low-noise, and low-cost resonant-type converter. Every technology that has been developed and reported so far has many disadvantages as well as advantages, and there are many problems to be solved before they can be put into practical use. In this paper, I am going to explain the structure of the partially capacitor input rectifier circuit that employs soft-switching operation that has been developed a new as the power-feedback-system one-converter circuit. These technologies have enabled us to put the power factor improvement for consumer-use electronic products into practical use.

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In this paper, we present the construction of a MRACS with the delta-operator for a pneumatic servo system in which the discrete-time model of the plant is non-minimum phase. Since the magnitude of neglected terms becomes negligibly small under the condition that the sampling-time is extremely short, the sampling-time must be chosen as short as possible. On the other hand, such a condition causes an insufficiency of the calculation-time for the identification of the unknown plant.
To overcome this problem, a multi-rate identification method in which identification-time is selected as multiple of the sampling-time is adopted here. To confirm the effectiveness of this approach, experiments were carried out using the existent pneumatic servo system.

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In most cases, PWM power factor corrected (PFC) converters are constructed by a diode rectifier and an active power circuit such as a boost or buck-boost chopper. Besides the PFC operation, the active power circuit can control the dc output voltage. The output voltage of the PAM inverters are controlled by varying the level of dc input voltage. A PAM method reduces the voltage and current stresses of the inverter and motors.
This paper proposes a new PAM inverter system with high power factor converter to obtain a sinusoidal input current. A Proposed PAM method to reduce the torque ripple in the induction motor can be reduced a switching losses by providing a pausing interval where the switching operation stops during a part of one period.

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Cardiac pacemaker has to be changed in three to five years for the battery life. A patients must be performed an operation whenever a patient is changed cardiac pacemaker. The method employing secondary rechargeable battery is researched to extend the battery life. The secondary rechargeable battery is transcutaneously charged from outside the body. This paper presents a transcutaneous energy transmission system for a rechargeable cardiac pacemaker battery. The transcutaneous energy transmission system is constructed with a high frequency resonant inverter, a transcutaneous transformer and a rectifier circuit. The secondary transformer is piled and the coupling coefficient and the conversion efficiency are measured with an experimental set up. The results show as follows. The best diameter of the primary center core is 15[mm]. The best output voltage frequency is 10[kHz].

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In a utility interactive photovoltaic (PV) generating system, a PWM inverter is used for the connection between the PV arrays and the utility. The inverter is controlled to keep the output power at the maximum point for the PV. Although the PV power can be easily found by using the measured PV voltage and PV current, the installation of two detectors in the system is indispensable to obtain the exact PV power. In the system operation with the maximum power which is fed into the utility, the PV does not always operate at the maximum point of the PV output power because of the power losses in the system. It has been reported that the use of the measured ac voltage or ac current in the inverter output side can exclude the system losses from consideration and achieve the system operation with the maximum utility power. In this manner, however, since the ac output waveforms of the PWM inverter consist of many pulse trains, the filter circuit may be necessary for the detector to get the exact values of the ac output.
This paper proposes a calculation method of the utility power in the PV generating system by using a PWM current source inverter. In this system, the PV current only is measured and is employed for the power calculation combining the control parameter of the PWM inverter. As the proposed manner monitors the utility power instead of the PV power, the control which does not need to take the system losses into consideration can be achieved. This paper presents the calculation method of the power for the single-phase inverter-PV system and gives the experimental basic characteristics. Moreover, the application of the proposed manner to the three-phase PWM inverter-PV system is shown and the experimental results are given.

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Recently, the two-degree-of-freedom (2DOF) control has been widely recognized to be efficient. The major merit of the 2DOF control is the independency between the tracking performance and the feedback performance. However, there is a limitation for the tracking performance in the 2DOF control system. In this paper, we propose new control system which consists of the conventional 2DOF controller and the learning controller. The role of the learning controller is to realize high tracking performance, which can not be realized only by the 2DOF controller. the learning controller can be designed only by using infomation of a specification for the 2DOF controller and it does not need information of the controlled plant. We show some experimental results to verify

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For the purpose of an automatic toll collection system for transportation services, a method of data re-allocation according to related entity in distributed communication systems is discussed. A simple model to formulate the movement of users (passengers or vehicles) along a transportaion network is proposed. Then the merits of user-ID based toll collection system is introduced. For the purpose of this user-ID based toll collection system, the re-allocation of data over a transportation network is required in order to reduce processing time at exit nodes. Some methods to implement this system and methods to evaluate their costs are studied.

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Lately, on the power rectifier circuit with semiconductor switching device, PWM control is generally employed for the purposes of reducing the harmonic currents on the DC side and improving the power factor of fundamental wave. In this case, the analysis of the current waveform becomes fairly complex. However, we express the PWM controlled voltage waveform by the step function, and can easily analyze the current waveform. We reported formerly some results of analysis about the waveform and harmonics of the current. In this paper, on the power rectifier circuit to which the nonequi-PWM and equi-PWM control are applied, we exactly calculate the harmonic currents on the DC and AC side, and the power factor by the use of the above analytical results. Thecharacteristics of both control methods are compared on condition that each controlled factor of the load voltage is equal. These results are shown in the calculated charts. The following items can be seen from these charts on the power rectifier circuit:
(1) The nonequi-PWM control can let the harmonic currents on the DC side decrease more than the equi-PWM control. But on the contrary, the harmonic currents on the AC side increase. Consequently, when the nonequi-PWM control is applied, the total power factor decreases by the increase of distortion factor of the current on the AC side.
(2) The difference between the harmonic currents on the DC and AC side to both of the nonequi-PWM and equi-PWM control increases with the increase of controlled factor of the load voltage.

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Magnetic bearings have many advantages of maintenance free, oil free and active dumping. Although these bearings are suitable for high speed machines, an increase in the shaft length of a motor with two magnetic bearings causes low critical speeds. A bearingless motor is a combined motor with a magnetic bearing, so the shaft length can be short. Radial force for position control is produced with superimposed (n±2)-pole flux on n-pole motor flux. Therefore, the radial force may be influenced with variations in motor current. If so, the radial control system may be unstable depending on load conditions.
In this paper, a model of a 5-axis controlled bearingless motor is shown. It is explained with the model that the transfer characteristics of radial position control have variations depending on the motor current. To control radial positions at any motor operations, a decoupling control method is proposed. The effectiveness of the proposed control system is confirmed in experiments.

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A flywheel rotor whose a main shaft had two pieces of flywheel disk and one magnet was designed and manufactured. The flywheel was made of CFRP material which is light weight and has high tensile strength. The magnet was hooped by CFRP in order to prevent from centrifugal burst. The rotor was suspended by a superconducting magnetic bearing in axial direction and active magnetic bearings in radial direction. The superconducting magnetic bearing was made of Y Ba₂Cu₃O_7-x which had a strong pinning force. It was stably accelerated up to 16, 500rpm by a induction motor in a vacuum chamber and then its energy storage value was 176Wh. The rotor design, bearing and rotational properties of the rotor was discussed.

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This paper describes a new type of high-power electrostatic motor based on skewed electrodes. The authors have developed several types of high-power electrostatic motors. Among them, Dual Excitation Multiphase Electrostatic Drive (DEMED) has the best performance in terms of power and its power/weight ratio is almost the same as those of the most advanced conventional electromagnetic motors. However, DEMED has large ripple of force and it leads to some defects such as low controllability, much noises and vibrations. To overcome those defects, the authors have proposed to apply skew technique to DEMED and have analyzed the effects of skewing electrodes. The analytical work have shown that the approptiate skewing can suppress the ripple of force considerably. In this paper, further analyses on the shape of electrodes are presented and a new type of motor depending on the analyses is fabricated and experimentd. Using the new DEMED with skewed electrodes, that is called V-DEMED, motion of the slider becomes much smoother, noises and vibrations become much smaller, and efficiency improves, without a lowering of thrust force.

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A novel study of mid-frequency oscillation and stability in permanent-magnet stepping motors is presented with an attempt to give a comprehensive description for the mid-frequency oscillation and the corresponding failure. It is shown that nonlinearity plays a crucial role in the mid-frequency oscillation, and relationship between local stability and mid-frequency oscillation is clarified. A sufficient and necessary condition of the local stability is given, which is more applicable than the existing results, and can be used to estimate the frequency range where the oscillation occurs. The separatrices are calculated and analyzed based on a 4th-order state-space model of stepping motor. The stability at high frequencies and failure are evaluated in terms of the calculated separatrix. A novel physical quantity, which is easily calculated and analyzed, is used to evaluate the high-frequency stability. The method and results developed in the paper are useful in understanding the complex oscillation and failure phenomena.

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For high-speed running in electric railway, reducing the contact loss of pantograph is one of the important problems. In order to investigate into the relations between contact loss and catenary vibration, and to work out an effective method, experiments and field tests have been carried out. From the results thereof, it is confirmed that contact force fluctuation comes under the influence of wave motion incident on pantograph. Therefore, at each hanger point, it is desirable that the energy consumption of wave motion be large and the reflection factor be small. A hanger which was developed to have spring and damping mechanism, such as rubber damping hanger or friction damping hanger, was found to be effective for damping the catenary vibration and reducing the contact loss.

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The authors have been pursuing the possibility of using a two-dimensional dc motor used for a driver of meal assist apparatus. In this paper, a new type do surface motor using window shaped coils (DSM) is proposed by the authors. And the thrust equations of the DSM is shown following the exciting method of the window shaped coils. The driving characteristics of the DSM are summarized as follows:
1. The maximum flux density of the air gap is calculated at 0.35 teslas when the exciting current is 1.8 amperes. The flux density achieves only 20% conpered with maximum flux density (1.8 teslas) of the yokes(SS41).
2. The thrust constant of the x-direction and y-direction are 2.93, 2.70 N/A respectively, so these difference is within only 8 %, And the maximum static thrust is over 5 newtons when the exciting current was 1.8 amperes.
3. It is recognized that the positioning control accuracy is good within 7.5% when the DSM is controlled by PD-control method.

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