Hiroyuki Ukai

Robust Trajectory Tracking Control of Elastic Robot Manipulators

In this paper, a robust control strategy is proposed for the trajectory tracking control of multi-link elastic robot manipulators. The robustness against both of the structured uncertainty caused by the nonlinear mechanical structure and the unstructured one caused by elasticity of links is taken into account in designing controllers. For this purpose the model of elastic robot manipulators is decomposed into the slow model and the fast model by using an integral manifold approach. The slow controller, which is robust against the structured uncertainty, is designed for the slow model on the basis of VSS theory. On the other hand, the fast controller, which is robust against the unstructured uncertainty, is designed for the fast model on the basis of H control theory. Then the composite control is constructed with the slow controller and the fast controller. Some results of numerical simulations are presented to show the effectiveness of this design procedure.

DSP- and GPS-based synchronized measurement system of harmonics in wide-area distribution system

With the recent progress in power electronics devices, harmonic pollution in the power system becomes a significant problem. Therefore, a great deal of attention has been paid to harmonic regulations and suppression technologies. As the utility power distribution system becomes broader and more complex, advanced harmonic measurement and analysis technologies are required. This paper presents the advanced measurement system of harmonics in a wide-area distribution system. The proposed measurement system has the following features. The measurement unit at each point in the distribution system consists of a digital signal processor as a high-speed processor and a global positioning system as a synchronization measurement. These units as terminals at multipoints in the distribution system are connected to the central monitoring station by the Internet. By using this system, the harmonic flows in the distribution system are measured and, hence, harmonic modeling can be realized in real time.

Observation of frequency oscillation in western Japan 60 Hz power system based on multiple synchronized phasor measurements

Western Japan 60 Hz power system is a longitudinal power system which consists of interconnected six major electric power companies. Though the power system has some interesting oscillation characteristics, there were few researches based on observation as a whole system. Authors have constructed an online global monitoring system of the power system dynamics, which is based on multiple synchronized phasor measurement technique using time stamp of the Global Positioning System (GPS) and Internet. This paper presents some results of observing system frequency oscillation and discussed the difference among the measured point. System dynamics due to the load frequency control (LFC) can be extracted from observed frequency oscillations by time-frequency analysis based on the Wavelet transform. Because variations of phase difference between the interconnected two areas are closely related with tie line power flow variations, relations between the frequency oscillations and the LFC are also investigated.

Improvement of steering feel of Electric Power Steering system with Variable Gear Transmission System using decoupling control

In this paper a new control method of electric power steering (EPS) system with variable gear transfer system (VGTS) is proposed. The control purpose is to achieve the desired steering gear ratio and the desired power assist with good steering feel. The basic idea of controller design is to apply decoupling control to this system and to separately design controllers for two decoupled systems. The angle control system and the torque control system are designed for the decoupled systems. In the angle control system the PID control is used for the desired gear ratio. In the torque control system the PID control is used for the desired assist torque designed so as to achieve good steering feel. In order to evaluate steering feel the Lissajous curve between the steering torque and steering angle is used. The steering feel of the proposed controller is verified by numerical simulation tests.

PMU based midterm stability evaluation of wide-area power system

Since the aspect of instability phenomena during midterm is complicated, the stability analysis is significant in order to keep the power system stable. Synchronized phasor angles obtained by the PMU (phasor measurement unit) provide the effective information for evaluating the stability of a bulk power system. This paper proposes a midterm stability evaluation method of the wide-area power system by using the synchronized phasor measurements. Clustering and aggregating the power system to some coherent generator groups, the stability margin of each coherent group is quantitatively evaluated on the basis of the one machine and infinite bus system. The midterm stability of a longitudinal power system model of Japanese 60 Hz systems constructed by the PSA (Power System Analyzer), which is a hybrid-type power system simulator, is practically evaluated using the proposed method.

Monitoring of Interconnected Power System Parameters using PMU based WAMS

In order to easily monitor the wide-area power system information covering many power producers, suppliers, and power companies, authors have been developed a PMU (phasor measurement unit) based WAMS (wide area measurement system). This WAMS momentarily gather information about the power oscillation affecting the stability of Japanese longitudinal power systems by signal processing of the power outlet phasor. This paper introduces the features of the PMU based WAMS, and an availability of the power outlet phasor is validated by comparing the measurements with actual power station. And as one of the applications, an estimation method of interconnected power system parameters from the monitored power oscillation information is proposed.

General servomechanism problems for distributed parameter systems

Abstract This paper investigates a general servomechanism problem for distributed parameter systems. The systems are described by linear differential equations in a Banach space applicable to both parabolic and hyperbolic equations. A feedback control law is determined in order to stabilize the resultant controlled system exponentially or strongly, and regulate output to reference outputs asymptotically in spite of un-measurable arbitrary disturbances. It is noted that the disturbances and the reference outputs treated here both belong to general classes.

Power System Dynamic Performance Measured by Phasor Measurement Unit

In recent years, there has been an increasing interest in monitoring and analyzing dynamic performances of power systems, such as observation of power system oscillations and evaluation of machine parameters. However, in Japan, there was little observation as a whole power system. In this paper the authors present a global monitoring system of power system dynamics by using the synchronized phasor measurement of demand side. Authors have placed phasor measurement units (PMU) connected to 100 V outlets in some universities in Japan and been researching into oscillation characteristics in power systems. Phasor measurements are synchronized based on the global positioning system (GPS) and measurement data are transmitted via Internet. Some oscillative features and variation of phasor in a day, a week or a year are analyzed using the acquired data. The purpose of this paper is to show a power system dynamic performance by the use of measurement data at an unexpected disturbance and monitors a global and a local oscillation mode.

Development of Rehabilitation Training Support System Using 3D Force Display Robot

In this paper we propose a new rehabilitation training support system for upper limbs. The proposed system enables therapists to quantitatively evaluate the therapeutic effect of upper limb motor function during training, to easily change the load of resistance of training and to easily develop a new training program suitable for the subjects. For this purpose we develop a new 3D force display robot and its control algorithms of training programs. The 3D force display robot has a parallel link mechanism with three motors. The control algorithm simulating sanding training is developed for the 3D force display robot. Moreover the teaching/training function algorithm is developed. It enables the therapists to easily make training trajectory suitable for the subject’s condition. The effectiveness of the developed control algorithms is verified by experiments.

Monitoring power system dynamics based on phasor measurements from demand side outlets developed in Japan Western 60 Hz System

Japan Western 60 Hz System consists of six major electric power companies. Due to its longitudinal structure there are some significant oscillation modes represented by long term oscillation among whole system. So far, some oscillative characteristics have been measured in own area or in the interconnected tie lines. However, there was little observation as a whole power system. In this paper the authors present a global monitoring system of power system dynamics by using the synchronized phasor measurement of demand side outlets, which are located in some universities in the 60 Hz power system. Phasor measurements are synchronized based on the global positioning system (GPS) and measured data are transmitted via Internet. Some oscillative features and variation of phasor in a day, a week or a year are analyzed using the acquired data.