International Journal of Applied Electromagnetics and Mechanics

Guest editorial to the ICMIT '01 special issue.

The purpose of our research is to design a communication system for ALS patients who have difficulty in using their hands and mouth. In the proposed system, eye blink is adopted as a switch to tell judging patient's intention by using several image processing. A list of intentions is displayed on the PC monitor; each intention is displayed with an adequate time interval. The patient can select the candidate intention by blinking his/her eye.

To investigate the efficiency of the proposed system, we conducted experiments on 10 subjects. The experimental results show that the proposed system distinguished conscious and unconscious eye blink.

Purpose: Many diseases such as bronchial asthma or pneumonia are detected by chest auscultation with a stethoscope. However, there are no obvious criteria for evaluating the chest auscultation findings. In the present study, chest auscultation findings were evaluated by digital computer analysis.

Material and method: "Crackle" was evaluated among abnormal respiratory sounds. Crackles with very short duration were extracted from recorded respiratory sounds, and FFT (Fast Fourier Transform) analysis was used.

Result: Spike-like waves could be recognized visually in the time-amplitude plot of respiratory sounds. The durations of each crackle ranged between 12.6 and 31.3 msec. The high/low-pitched sound ratio calculated by FFT analysis ranged between 0.059 and 3.24.

Conclusion: The characteristics of crackles could be evaluated objectively by computer analysis. The high/low-pitched sound ratio correlated with the computed tomography (CT) findings and the ratio is useful for differential diagnosis of the disease.

This paper presents the development of a mechanical SMA urethral valve driven by a portable transcutaneous energy transmission system, which is powered by batteries. Structure of the valve was improved by introducing a bite mechanism in order to prevent the pinch of urethra by the valve. The cycling characteristics and energy transmission efficiency were examined by laboratory tests. Experimental results show that the stable operation can be obtained by introducing a voltage regulating circuit to the energy transmission system and utilizing the sinusoidal oscillation in the energy transmission system can enhance the transmission efficiency. Furthermore, the function of the valve system was tested by the vitro and vivo animal experiments.

Although it is possible to achieve higher resolution by conventional ultrasonic technique, it suffers from a disadvantage because testing has to be performed in a liquid medium. In contrast with the conventional technique, a dry-contact ultrasonic technique, which can be carried out without wetting the testing parts, is preferable. In a new technique that is developed by the authors, a dry-contact interface is used by inserting a membrane between water and the tested parts. Experiments were also carried out in search of membrane that can transmit higher frequency components. Dry-contact ultrasonic transmission using two kinds of plastic films and a silicone rubber sheet was performed on an acrylic resin. It was shown that the plastic films far excel in transmitting higher frequency components than the silicone rubber sheet.

The yield rate in fabrication of TFT LCD's (thin film transistor liquid crystal display) with high pixel density is strongly dependent upon the effectiveness of precision cleaning method. Ultrasonic cleaners operating at high frequencies (typically above 1 MHz, megasonic cleaners) are known to be effective in removing submicron contaminants without causing mechanical damage to the surface. In this study a megasonic cleaner for TFT LCD manufacturing process is developed and its performance is evaluated through experiments. The experimental results show that the developed megasonic cleaner is effective in removing very small particles from the LCD panels.

This paper represents the development of a distributed flexible tactile sensor using PVDF (polyvinylidene fluoride) film. The tactile sensor which has 8 × 8 tactile elements is fabricated using PVDF film and flexible circuitry. Experimental results on static and dynamic characteristics are obtained. In order to investigate the characteristics of the tactile sensor, the output of the tactile sensor is measured by applying arbitrary forces and frequencies those are excited to the shaker. In the static characteristics the threshold and the linearity of the sensor are investigated. Also the dynamic response of the sensor subjected to the variable frequencies is examined. The signals of a contact pressure to the tactile sensor are sensed and processed in the DSP system in which the signals are digitalized and filtered. Finally, the signals are integrated for taking the force profile. The processed signals of the outputs of the sensor are visualized in personal computer, the shape and force distribution of the contact object are obtained using two and three-dimensional image in real time. The reasonable performance for the detection of contact state is verified through the experiment.

Requirements for Distributed Monitoring and Control Networks (DMCN) differ greatly from those of typical data networks. Specifically, any DMCN technology which employs a fieldbus protocol is different from IP network protocol TCP/IP. In general, one needs to integrate fieldbus protocol and TCP/IP to realize DMCN over IP network or internet, which can be viewed as Virtual Device Network (VDN). Interoperability between devices and equipments is essential to enhance the quality and the performance of predictive maintenance (PM). This paper suggests a basic framework for VDN using DMCN over IP network and a method to guarantee interoperability between devices and equipments.

This paper describes an active electromagnetic levitation control of a flexible beam using current and magnetic flux instead of a position sensor. An observer is used to estimate the position based on current, magnetic flux, fundamental, 1st and 3rd modes of vibration of the beam, and input voltage to the electromagnet. The controller combines state-feedback with the observer output to arrive at a new input voltage. Results obtained with a conventional observer and disturbance observer are discussed. Simulation and experimental results demonstrate the feasibility of the approaches.

In this paper, a robust control scheme for a class of nonlinear dynamical system is proposed by using output-feedback linearization method. The presented control scheme is based on the VSS. We assume that the nonlinear dynamical system is minimum phase, i.e., the relative degree of the system is p=r_1+r_2+ … +r_m ≤ n and zero dynamics is stable. We also assume that the states of zero dynamics are not accessible. It is also shown that the global asymptotically stability is guaranted. And we verified that the proposed control scheme is then applied to the control of a two degrees of freedom (DOF) robotic manipulator with payload.

This paper is concerned with robust control of a quad-rotor aerial vehicle attitudes (pitch, roll, yaw). Attitudes of the quad-rotor vehicle is affected by various sources of disturbances such as wind and ground effect. In this paper, we propose a new disturbance observer so that these disturbances are estimated and compensated by the disturbance observer. It is shown by simulations that the proposed disturbance observer effectively compensates disturbances.

This paper proposes a shortest path generation scheme for point stabilization of the car-like robot. An implicit shortest point stabilization algorithm has been suggested conceptually by Vendittelli. As an extension, we present an algorithm which is more explicit and faster than previous one. Our scheme provides exact equations for practical implementation. Moreover, its computation time is remarkably lower than the previous one for the case in which the final point changes frequently. We provide a proof of the optimality and validate the performance of our algorithm through the simulation and experiment.

In this paper, a new distributive lighting control system for BA(Building Automation) is presented. For optimal lighting control and saving energy in buildings such as hotels, schools and offices, the group and pattern lighting control as well as individual lighting control at one time are required. All the modulated lighting control terminals are connected to the central control unit through a pair of power lines. These power lines provide both power and signals to the each distributed terminal, and data are transmitted using the cyclic time division multiplex transmission algorithm. With this algorithm, a low-cost distributive control system for lighting applications has been achieved, allowing energy and maintenance saving and increasing the reliability of the lighting control system.

In this paper, we propose a new structure for a binary data transmission using the neural network and Haar transform to reduce the noise and distortion in the channel. To solve the problems such as signal distortion and nonlinearity during the transmission and reception of the signal, we use the neural network to design an equalizer to adapt the change of the channel characteristics. Before transmitting digital information, two adjacent binary signals are Haar transformed and are sent to the channel which is assumed to corrupt the signal by an additive white Gaussian noise (AWGN), and then we receive the noise-reduced signal through the inverse Haar transform. We analyze the probability of error and simulate the model to show the validity.

The time derivative of acceleration, sometimes called a jerk, plays an important role in vibration control, ride comfort evaluation and so on. It is usually required to estimate a jerk from a noisy acceleration signal. Simple numerical differentiation of a filtered acceleration signal often fails to give satisfactory result. A model-based estimation technique is proposed in this paper. Behavior of a jerk signal is modeled by a random walk process. Then the problem of estimating the jerk is formulated as a state estimation problem. On the assumption that the observation noise has a colored noise component, a Kalman filter and an filter are derived for estimating the jerk. The performances of both estimators are compared by simulation. Although both filters provide comparable performances for ideal case, the filter with appropriate use of a priori information has better robustness than the Kalman filter and is more useful in real applications.

This paper investigates multi layer neural networks that involves the chaos neurons to achieve high efficiency of neural networks learning. Two types of neural networks are proposed. One of the multi layer neural network has the chaos neural network in its hidden layer. The other multi layer neural network is composed only using the chaos neurons. The learning ability of the neural networks involving the chaos neurons and/or chaos neural network is evaluated by benchmark experiment with XOR problems. Experimental results show the feasibility of the chaos neurons to improve the learning of neural networks. As an engineering application example, the multi layer chaos neural network is applied for identifying nonlinear dynamical systems and its effectiveness is demonstrated.