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We are planning to develop the new Advanced Distribution Automation System (ADAS) equipped with optical communication network and sectionalizer with sensor for more grid reliability and efficiency on maintenance operation. The new system is featured with the function of fault cause or damaged part estimation. The new sectionalizer captures the waveform of electrical line surge originated by fault and the system analyzes the waveform for this function. This paper mainly introduces the system configuration of ADAS and an early stage examination of fault cause estimation technology. [ABSTRACT FROM AUTHOR]

This paper describes accurate position control in an object coordinate system. When motion control of an industrial robot placed in a global coordinate system is taken to be in an object coordinate system, it is preferable and convenient to decide its motion by having the operator teach the robot. However, the teaching procedure requires considerable time and effort. Moreover, whenever the relative position between the robot and the object is changed, the operator needs to teach the operation again. To improve the above issue, a strategy that decides the robot motion without the teaching must be developed. This paper proposes a control strategy that does not require teaching and enables the creation of the desired motion without affecting the relative position error between the robot and the target object in object coordinate space defined by a PSD (Position Sensor Detector). In the proposed approach, the estimation algorithm of the kinetic transformation between the global and the object coordinates is introduced by using PSD output, and the error of coordinate transformation estimated by the proposed approach is compensated for in the global coordinate system. The validity of the proposed method is shown using simulations and experiments. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(3): 53–61, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20354 [ABSTRACT FROM AUTHOR]

This paper considers a human-operated task model based on identification techniques using switched systems expressed by mixed logical dynamical systems. In the system, each subsystem is expressed by a piecewise affine system. For a model to be identified, it is not easy to determine a number of subsystems in advance. In this paper, we propose a simultaneous identification technique which takes into account both a number of subsystems and parameters, so that a piecewise affine model of a human operation can be obtained. In addition, the obtained model is applied to automation. The effectiveness of the proposed method is illustrated by simulations and experiments. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(1): 46-54, 2011; Published online in Wiley Online Library (). DOI 10.1002/eej.21079 [ABSTRACT FROM AUTHOR]

This paper presents an expression of system connection considering transmission delay. In a research field of decentralized system or information system, the expression method of the system connection is a very important issue. Therefore, several expression methods of system connection have been proposed so far. However, those expressions are mainly based on binary operations without consideration for the transmission delays on connection paths although the concept of time is very important for expression of system connection. In this paper, expression methods of system connection considering transmission delays on the paths are proposed. Those expressions are based on exponential-type expression and can express both connections and transmission delays. Furthermore, the expression that can express connections, transmission delays, and past subsystems is also proposed. As one example of the application of proposed expressions, application for path selection of the design of network-based control system is described. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 45–54, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20839 [ABSTRACT FROM AUTHOR]

In industrial motor drive systems such as industrial plants and industrial robots, a torsional vibration often is generated because of the elastic elements in torque transmission. This vibration makes it difficult to achieve quick responses of speed and may result in damage to the plant. Such systems simply are modeled as two mass system. The shaft torque feedback system with the disturbance observer, which is called "resonance ration control," is proposed to suppress the vibration for the two-mass system. In this paper, the design of controller gains in the shaft torque feedback system is examined considering not only the control performance such as the vibration suppression and dynamic responses, but also the robust stability against the noise and the model uncertainties. This paper shows the validity of the control system and the examinations by several experiments. [ABSTRACT FROM AUTHOR]

SUMMARY Recently, interest in energy savings in railway systems has been increasing because of its environment-friendly aspects, for example, CO2 emissions. In this paper, the authors propose a scheduling and control system for automatic train operation (ATO) that saves energy. This research in ATO concentrates on the optimization of speed profiles to save energy. The differences in this system from previous work are substantiative experiments on the track and a design that explicitly considers the following energy-saving operations. First, coasting is installed in speed profiles and maximum speed is decreased by jerk regulation. Second, power-limiting braking is used in the braking section and regenerative energy is increased. To achieve this braking efficiency, notch operations are updated. Finally, second-order scheduling is achieved by high speed control using ATO. For the experiments on the track, the efficiency of a linear-motor train was measured in a pre-experiment and used to perform accurate numerical calculations. In conclusion, the numerical study shows an energy efficiency increase by 7.3% and the plan for further experiments is determined. [ABSTRACT FROM AUTHOR]

This paper describes a novel straight and circular road driving control scheme for electric power-assisted wheelchairs. “Electric power-assisted wheelchair” which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the performance of straight and circular road driving must be further improved because the two wheels drive independently. This paper proposes a novel driving control scheme based on fuzzy algorithm to realize stable and reliable driving on straight and circular roads. The suitable assisted torque of the right and left wheels is determined by fuzzy algorithm based on the posture angular velocity of the wheelchair and the human input torque proportion of the right and left wheels. Some experiments on the practical roads show the effectiveness of the proposed control system. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 36–44, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20846 [ABSTRACT FROM AUTHOR]

A new circuit of parallel-type voltage sag compensator is proposed in this paper. The proposed voltage sag compensator can reduce the necessary capacity of the energy storage capacitor for compensation by boost-type power factor correction rectifier charging the capacitor during a voltage sag. As a result the proposed system can reduce the size and maintenance of the apparatus. Copyright © 2004 Wiley Periodicals, Inc. This paper shows the principle and control system of the proposed circuit. Compensation characteristics were demonstrated by simulation and experiment. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 19–33, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20261 [ABSTRACT FROM AUTHOR]

This paper proposes a new robust feedforward tracking servo system for optical disk recording systems in the case of a sudden disturbance for the optical disk recording system. In optical recording systems, the tracking servo system must suppress tracking error below its tolerance. This paper designs the robust feedback control system by using the coprime factorization and disturbance observer. The proposed robust feedback control system suppresses the sudden disturbance caused by walking and running. The detecting signal of optical disk recording systems is only a tracking error. Hence, the feedforward controller of the proposed tracking control system is constructed based on both Zero Phase Error Tracking (ZPET) control theory and prediction of tracking error. The experimental results point out that the proposed tracking servo system has a quick and precise tracking response and keeps the residual tracking error below its tolerance. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(4): 60– 68, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20257 [ABSTRACT FROM AUTHOR]

In recent years, legged robots have progressed and are able to walk just like human beings. Hopping offers a possibility of moving faster and avoiding larger obstacles than walking. Thus, hopping becomes more significant. Copyright © 2004 Wiley Periodicals, Inc. In this paper, to take account of torque limits of motors, we propose the method of controlling the hopping height by changing the leg length at bottom. Considering an actual environment, the environment will change as the robot moves around. Therefore, we describe a way to estimate the actual thrust force. Using the estimated thrust force, command value of leg length in the landing phase is determined. The effectiveness of the proposed method is confirmed by simulation and experimental results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 64–71, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20172 [ABSTRACT FROM AUTHOR]

Recently, consumers have shown concern about the reliability of electricity to be served. For example, some consumers need electricity with a higher reliability via automation of manufacturing processes. On the other hand, some consumers need electricity at a cheaper price even if the reliability becomes a little worse. Under such circumstances, it is necessary that power suppliers evaluate the needs of every consumer precisely and propose the most desirable measures for meeting their requirements. This paper develops a tool to analyze the reliability for high-voltage supplied consumers quantitatively. Further, this paper presents a method for evaluating the outage cost of consumers to help them choose the most appropriate measures for maintaining reliability. The proposed method applies the fuzzy reasoning approach. The validity of the proposed method is ascertained through some numerical simulations. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 41–51, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20137 [ABSTRACT FROM AUTHOR]

This paper proposes a new position-sensorless position control method for high-speed spindle drive systems. Mechanical vulnerability of position sensors such as an encoder mounted on a spindle motor is becoming a serious problem as required speed increases. For high speeds above 1500 rad/s, sensorless drive is preferred. It is possible for current technologies to control spindle motor in speed control mode without the sensor, but not in position control mode without the sensor. In the example of high-speed spindle systems of automatic machine tools, implements must be automatically attached to and removed from the spindle at standstill. Automation necessitates position control, for which current technologies require a sensor. The proposed method makes it possible to realize pure sensorless high-speed spindle systems performing in both speed and a position control modes. The method can attain a position control performance with quick settling from speed control and a repetitive positioning precision of 0.006 rad, 0.4°, which is comparable to that achieved by current sensor-based methods. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(3): 58–69, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10059 [ABSTRACT FROM AUTHOR]

Programmable Controllers (PCs) are widely applied in the control of manufacturing systems. The purpose of this paper is to give some basic concepts for the verification of sequential control systems. In particular, we propose the modeling method of the Ladder Diagram (LD) with cyclic scanning of the PC by Petri Nets (PNs). First, some experiments are conducted to examine the relationship between the cyclic scan and the behavior of the LD. Second, PNs are used for qualitative modeling of the behavior of the LD, based on IEC61131-3. In addition to LD Boolean logic expressions, we consider PC operation, described by the cyclic scan, peripherals, memories, and scanning ladder rungs. It is shown that the difference between the LD description and the behavior caused by the cyclic scan can be represented by the proposed PNs. Moreover, the behavior of the PNs can be analyzed by firing sequences, and is confirmed to be in good qualitative agreement with the experimental results. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(4): 79–86, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.1169 [ABSTRACT FROM AUTHOR]

Learning automata select an action from a finite set of their available actions and update their strategy on the basis of response received from the random environment using what is known as a reinforcement scheme. As an environment changes, the ordering of the actions with performance criterion may vary. If a learning automaton with a fixed strategy is used in such an environment, it may become less expedient with time and even inexpedient. However, using the learning scheme that has sufficient flexibility to track the better actions makes the performance improved. In this paper, a variable structure learning automaton network with periodic random environment is proposed. The results of some numerical simulations show that our model can be used for tracking some periodic nonstationary environment for which an upper bound on the period is known. © 1999 Scripta Technica, Electr Eng Jpn, 129(1): 39–45, 1999 [ABSTRACT FROM AUTHOR]

Clock feedthrough (CFT) error is one of the most important problems for switched current (SI) circuits. This paper proposes a SI circuit which can reduce CFT error drastically. The proposed circuit will theoretically reduce both signal-dependent and independent errors by using CMOS switches under a fixed and appropriate bias. Although conventional circuits based on a similar idea need operational amplifiers or additional capacitors, our proposed circuit requires only MOSFETs. The proposed circuit can reduce CFT current with less power consumption and chip area compared to those of conventional circuits. An automatic tuning circuit, which controls the gate potential appropriately, is also proposed. Simulation results demonstrate the effectiveness of the proposed circuits. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 21–29, 1999 [ABSTRACT FROM AUTHOR]

The speed control ability of dc servomotors is affected by parameter variations and disturbance torque. In this paper, a robust speed control method for dc servomotors with a disturbance torque observer and a feedback controller is proposed. The disturbance torque observer is used for the compensation of parameter variations and disturbance. The feedback gain is adjusted in the aspect of stability by an adaptive gain law based on Lyapunov's direct method and is used to restrain the influence of estimation error for the disturbance observer. A robust current control scheme for a voltage source PWM inverter with disturbance observer is also presented, since current control ability affects the control performance of dc servomotors. The validity of this control scheme is verified by numerical simulations and experiments. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 30–40, 1999 [ABSTRACT FROM AUTHOR]

Recently, many kinds of magnetic levitation systems have been proposed and developed for use in factory automation systems. This progress in the development depends on the appearance of new types of permanent magnets and new control theories. On the other hand, some systems have simple structures in which couples roles are given for both levitation and conveyance. As for these systems, however, many trials are needed to establish the system configurations and the control theory. The authors have developed a new magnetically levitated carrying system driven by LIM (linear-induction motor). The system can be completely detached from a guideway both in mechanical and electrical meanings. In this paper, the experimental results, especially the driving characteristics of a vehicle without any contacts to the LIM guideway, are discussed. [ABSTRACT FROM AUTHOR]

With the progress in factory automation in industry has come the demand for higher speed drive and performance for an AGV (automated guided vehicle). A new steering control of the AGV by fuzzy control has been proposed to replace the PI control. However. much time is required to investigate the regulations and to adjust the scaling factors for excellent performance in the fuzzy control, In this paper, a new steering control for an AGV based on the neural network using the backpropagation method is proposed. The good steering control results by the fuzzy control are adopted for the teaching signal of the neural network. First, the effect of the number of learning and the learning errors on the steering control results are discussed by computer simulation using the AGV model. Further. the ability of generalization in the turning radius and the traveling speed also are investigated. It becomes clear that the AGV can travel along a designated route provided the neural network learns both the right and left turning at the maximum traveling speed and the minimum turning radius. Then it is proved by an experiment using the AGV constructed for the test that the proposed steering control method is very affective. [ABSTRACT FROM AUTHOR]

SUMMARY More and more dispersed power sources will be introduced to achieve a low-carbon society. However, many problems may occur as a result of excessive introduction in the current power system. For example, delays or failures of fault detection may occur due to a decline in protective relay sensitivity. This paper proposes a new system of protective relays for distribution lines using section switches with sensors to solve the problem. In addition, experimental results on the proposed system composed of Intelligent Electronic Devices based on IEC 61850 are presented. [ABSTRACT FROM AUTHOR]

SUMMARY In recent years, the reduction of total cost of ownership (TCO) from system architecture to start-up, operation and maintenance has risen rapidly with the demand for factory automation (FA). But due to the complexity and combination of functions of machines and devices, and to progress in meeting high-speed and high-accuracy demands, networking of controllers and amplifiers has come into use. However, conventional servo networks have had various problems in TCO reduction. The servo network proposed in this paper can obtain position and speed information from counterpart amplifiers in the synchronous control by communication between amplifiers, which is conventionally unattainable. Compared with the conventional system, high-speed, high-accuracy operation can be realized with the new synchronous compensation control utilizing data transferred between amplifiers, and improvements in operating productivity were verified with an actual machine. Conventional systems used multiple electrical signals, but the new network realizes optical communication over only a single pair of optical cables using optically isolated circuit technology, and it has also proved effective for increasing productivity in the setup and maintenance. [ABSTRACT FROM AUTHOR]

In this paper, the robust tracking control problem for a rigid robot with discontinuous uncertainty is considered. The controller design approach is based on Filippov's framework and generalized Lyapunov stability theory. It is shown that no Lipschitz continuous controller to stabilize the error system asymptotically exists because of the existence of nontrivial equilibrium set including the origin. A robust controller which makes the error system asymptotically stable is derived in Filippov's framework. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(4): 53–61, 2008; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/eej.20303 [ABSTRACT FROM AUTHOR]

This paper describes the generation of adaptive gait patterns using new Central Pattern Generators (CPGs) including motor dynamic models for a quadruped robot under various environments. The CPGs act as the flexible oscillators of the joints and adjust joint angles to required values. The CPGs are interconnected with each other and sets of their coupling parameters are adjusted by a genetic algorithm so that the quadruped robot can realize stable and adequate gait patterns. Generation of gait patterns results in the formation of the CPG networks suitable for the formation of not only a straight walking pattern but also of rotating gait patterns. Experimental results demonstrate that the proposed CPG networks are effective for the automatic adjustment of the adaptive gait patterns for the tested quadruped robot under various environments. Furthermore, the target tracking control based on image processing is achieved by combining the general gait patterns. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 35–43, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20225 [ABSTRACT FROM AUTHOR]

Circuit simulators have often been used for power electronic system design. However, most of them are limited in their application class to one with fixed elements because they can only handle programmed or fixed element characteristics. To overcome this disadvantage, a simulator should be flexible enough to handle any combination of characteristics of available mathematical functions and operations. It is a problem how to compute Jacobian elements or partial derivatives with respect to circuit variables. This paper proposes a way to compute the derivatives by using the automatic differentiation method which is simple and accurate. The principle and application examples are described. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 47–54, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20075 [ABSTRACT FROM AUTHOR]

This paper describes the automatic generation of system descriptions for SCADA (Supervisory Control And Data Acquisition) systems. The proposed method produces various types of data and programs for SCADA systems from equipment definitions using conversion rules. First, it makes directed graphs, which represent connections between the equipment, from equipment definitions. System descriptions are generated using the conversion rules, by analyzing these directed graphs, and finding groups of equipment that involve similar operations. This method can be used with various SCADA systems, and provides visual tools for editing conversion rules. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(3): 29–37, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10149 [ABSTRACT FROM AUTHOR]

A type of mag-lev system with permanent magnet motion control is proposed, analyzed, and examined experimentally. In this mag-lev system, the levitating object hangs on the upper iron rail and such parts as magnets, sensors, and actuators are installed on the object. This levitation method is very useful for noncontact conveyance systems, because the conveyance path is very easy to make. This paper describes the success of the construction of the hanging-type magnetic levitation system using magnet motion control mechanism. © 2000 Scripta Technica, Electr Eng Jpn, 133(3): 63–70, 2000 [ABSTRACT FROM AUTHOR]

In high-level synthesis, scheduling is an important stage which assigns each operation appearing in a data flow graph to a specific control step, whose results influence the design quality directly. This paper describes a scheduling approach for pipelined datapaths. Since few previous approaches estimate the interconnection cost between register (register-to-register cost), our approach introduces a datapath model with interconnection between registers across buses, and minimizes the total hardware cost including the register-to-register cost by force-directed scheduling. © 1999 Scripta Technica, Electr Eng Jpn, 128(3): 63–71, 1999 [ABSTRACT FROM AUTHOR]

A magnetic supension system with linear actuators and permanent magnetics (instead of electromagnets) has been development. In this system the bearing forces are controlled by adjusting the air gaps between permanent magnets and the levitated (a circular disk). This system uses less energy and exhibits none of the over-heating of coils typical of systems employing electromagnets. This paper describes a disk suspension system with three degrees of freedom. The system can operate either with a decentralized (distributed) feedback control system or with a centralized (lumped) one. Feedback gain matrices are calculated for each type of control system. The performances of the types of control systems are compared by numerical simulations and experiment. This work is part of an effort develop a magnetic levitation conveyer system. [ABSTRACT FROM AUTHOR]

This paper presents the robust control design of a magnetic suspension system For a Flexible beam which is a simplified model of an elastic rotor in a magnetic bearing system. To stabilize this magnetic suspension system which is unstable in nature, the H∞ control theory is applied for a design of the control system. TO apply the H∞ control theory, a state-space model of an augmented plant with frequency-weighting functions is constructed. This augmented plant has two inputs which are the exogenous inputs and the control inputs, and two outputs which are the sensor outputs and the regulated outputs. Here we consider the mixed sensitivity problem. The H∞ controller is implemented by a digital controller which is able to execute the computations very quickly. For the evaluation of the control performance, several experiments are made. The robustness of the closed-loop system is confirmed by the experimental results. The result of this study is useful for the control design of a magnetic hearing system. [ABSTRACT FROM AUTHOR]

The electric railway is an environment‐friendly transportation system. An energy‐saving operation with a low cost and high energy‐saving efficiency is often considered to further decrease energy consumption. An Automatic Train Operation (ATO) system has the advantage of energy‐saving because a train can be controlled by an on‐board computer. However, many railway lines are still being operated by drivers and controlled via manual operation in addition, energy managements often become difficult for drivers and operators. Therefore, a study of energy‐saving manual operation is desired. Energy verification of a manual operation is difficult because an adequate experiment has several constraints and trial periods are limited. Moreover, it requires a considerable amount of time and effort. In this study, an energy evaluation system is developed to calculate the energy consumed by a train when a driver manually operates it through adding an advanced calculation device to a conventional railway simulator. Consequently, the evaluation system contributes to carry out simple experiments with a short duration. [ABSTRACT FROM AUTHOR]

SUMMARY Aimed at providing small high-power motors with excellent efficiency, a motor stator with rectangular-wire lap windings and an automatic process for its production were developed. The structure of the windings, namely, two continuous 'α-shaped' coils, and the coil-production method (involving simultaneous coil forming and coil insertion) enable mass production of this stator. The slot-fill rate for a prototype stator was 80.5%, and the total height of the coil ends was 60 mm to 72 mm. On the basis of the ratio of the sectional areas of two types of the motors, its efficiency was estimated to be 3.7% higher than the efficiencies of motor stators with round-wire concentric windings (at a rotation speed of 1000/min). In addition, the number of coil parts and the number of welding points were greatly reduced compared to those of a stator with segmented-coil wave windings. [ABSTRACT FROM AUTHOR]

An automatic design method for power systems to control electric loads required by customers and to ensure the power supply for the loads is described. This method features (I) an electric unit model including the possible connections among the electric units, (II) knowledge association networks to reduce maintenance cost of the knowledge base and to improve efficiency in selecting/specifying electric units, (III) a planning algorithm to find electric paths to control the electric loads and to ensure the power supply, and (IV) the reactive redesign of the automation of editing power systems. APEC3 (Advanced Plant Engineering Cycle tool version 3) is an automatic design tool for power systems that supports electrical engineering processes in developing single line diagrams, specification balance statements (design rationales), and item lists. When engineers modify unit specifications, APEC3 invokes the redesign function which automatically changes the specifications of all relevant units. To evaluate the effectiveness of the method, APEC3 was used in designing practical power systems of steel plants. The results showed that APEC3 can reduce the design time to one-eighth that of the usual design time. Therefore, the engineers can find optimal specifications of the power systems by evaluating a number of possibilities. © 2002 Scripta Technica, Electr Eng Jpn, 139(2): 36–45, 2002; DOI 10.1002/eej.1151 [ABSTRACT FROM AUTHOR]

This paper proposes a method of maintaining the stability of robotic manipulators with network connection which are doing cooperative tasks. Such robotic manipulator systems have many possibilities, but they sometimes fall into unstable states due to double connection, that is, mechanical and informational connection. To avoid such unstable oscillations, the proposed method utilizes a kind of torque limiter and a notch filter. © 1997 Scripta Technica, Inc Electr Eng Jpn, 121(2): 47–53, 1997 [ABSTRACT FROM AUTHOR]

To improve the electricity service reliability, a distribution line state monitoring system has been developed. It is composed of a central control unit, remote control switches, the slave unit and monitoring sensors. The first system employed fiber-optic voltage and a current sensor. The latest system employs a unique form of cost reduction, with no voltage sensors incorporated. This system can detect the grounding direction by the information of the phase difference between the line-to-line voltage and I0 provided by the monitoring sensor, and grounded line information (64φ) from the substation. Installation of the system has been underway since 1992. [ABSTRACT FROM AUTHOR]

Power flow calculation is a basic tool for power system planning and control which includes power flow analysis, voltage control, service restoration, network reconfiguration, and other operation functions for control centers. In these applications, it is very important to solve the power flow problem as efficiently as possible. [ABSTRACT FROM AUTHOR]

Tracking control problem of multiple mobile robots is considered. Our system is composed of a reference and follower robots of unicycle type. The robots are assumed to satisfy pure rolling and nonslipping conditions, which lead to nonholonomic constraints. The purpose is to control the followers so that the reference is tracked with arbitrary desired clearance and also to avoid interrobot collisions. To accomplish this goal, we first introduced a virtual robot (VR) tracking control to establish and maintain the formation when no collision is detected. VR is an ideal robot fixed with each follower and helps in simplifying the control, as the tracking error becomes zero in the final stage. During the process, if the possibility of collision is detected, a collision avoidance technique (l-ψ or l-l control) will be applied to the lower priority robot. The result of this control gives a monotonic convergence in an internal shape of distance variables, which enables us to predict the movement of the robots during this control and leads to collision-free movement. These processes are repeated until the desired motion is accomplished. Simulation results prove the efficiency of our control techniques. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(3): 81–88, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20192 Copyright © 2006 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A combined cycle power plant which combines a gas turbine and a steam turbine can achieve high energy efficiency. Many combined cycle plants have been installed worldwide. However, a large-scale blackout due to combined cycle chain trip-out occurred in Malaysia in 1996. The cause of this chain trip was considered to be a large drop of system frequency. Thus, there is a need to investigate the stability of the combined cycle power plant for the frequency drop. Several dynamic models of a combined cycle plant have been proposed. In our analysis, we use some of them and build a model for a single-shaft combined cycle plant. We execute numerical simulations to see how the combined cycle plant behaves when the system frequency drops. The cause and the countermeasure of the combined cycle plant trip-out are explained. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(3): 9–19, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10117 [ABSTRACT FROM AUTHOR]

Dual mode synchronous positioning control with switching of master and slave axes is proposed to realize accurate contour control of industrial robot arms. The axis which is contaminated with disturbance is selected as the master axis, then the disturbances in both first axis and second axis can be compensated. The effectiveness of the proposed method was verified by experimental results of an actual articulated robot arm. © 2001 Scripta Technica, Electr Eng Jpn, 138(2): 33–40, 2002 [ABSTRACT FROM AUTHOR]

A method for calculating the single-step response of five-phase hybrid stepping motors is obtained. The effects of winding connecting methods—(1) star-bipolar SB, (2) pentagon PD, and (3) new pentagon NP—on the single-step response are investigated. By application of the above calculation method, the continuous rotating characteristics are studied. It is found that the maximum slewing pulse rate of NP is higher than that of SB and PD connections, and that the variation of the rotor speed at high speed with the SB and PD connections is larger than that with the NP connection. The effects of the current waveform on the oscillation characteristics and relations between the current waveform and the winding connections are investigated. © 2001 Scripta Technica, Electr Eng Jpn, 136(1): 47–56, 2001 [ABSTRACT FROM AUTHOR]

Focuses on the input layer optimization of neural networks by sensitivity analysis and its application to recognition of numerals. Usage of image recognition equipment in the field of factory automation for electronic parts assembly and product defect tests; Development of a recognition algorithm for such application; Discussion of the input-to-output sensitivity of the neural net.